Autism vs ADHD vs Developmental Delay

Understanding the Differences in Children

If you’ve started noticing differences in your child’s development, one of the most common questions is:
“Is this autism, ADHD, or just a delay?”

This can feel confusing — especially because many signs overlap.

​This guide will help you understand the key differences, while also explaining what to do next.
Why These Can Be Confusing

Autism, ADHD, and developmental delays can look similar in early childhood.
For example, a child might:
  • Not listen
  • Have delayed speech
  • Struggle with attention
  • Find social situations difficult
But the reason behind these behaviours is often different.
What Is Autism?

Autism (Autism Spectrum Disorder) is a neurodevelopmental condition that affects:
  • Communication
  • Social interaction
  • Behaviour and interests
  • Sensory processing

​Common signs of autism:
  • Differences in communication (e.g. delayed speech, limited gestures)
  • Difficulty with social interaction
  • Repetitive behaviours or strong routines
  • Sensory sensitivities
Learn more: ​
What Is ADHD?

ADHD (Attention-Deficit/Hyperactivity Disorder) affects:
  • Attention
  • Impulsivity
  • Activity levels

Common signs of ADHD:
  • Difficulty focusing or sustaining attention
  • Easily distracted
  • Impulsive behaviour
  • High energy or constant movement
Children with ADHD usually want to engage socially, but may struggle to regulate their behaviour.
What Is a Developmental Delay?

A developmental delay means a child is developing skills more slowly than expected for their age.
This can affect areas like:
  • Speech and language
  • Motor skills
  • Learning
  • Social development
Key point: A delay may catch up over time, or may indicate an underlying condition.
Key Differences at a Glance

Communication
  • Autism: Differences in communication and social use of language
  • ADHD: Talks a lot but may interrupt or go off-topic
  • Developmental Delay: Slower development of communication skills​

Social Interaction
  • Autism: Differences in understanding and engaging socially
  • ADHD: Wants to engage but may struggle with impulse control
  • Developmental Delay: May interact at a younger developmental level

Behaviour
  • Autism: Repetitive behaviours, strong routines
  • ADHD: Impulsive, hyperactive, difficulty sitting still
  • Developmental Delay: Behaviour aligns with developmental stage

Attention
  • Autism: May focus intensely on specific interests
  • ADHD: Difficulty sustaining attention across tasks
  • Developmental Delay: Attention may be age-delayed

Sensory Differences
  • Autism: Often significant sensory sensitivities
  • ADHD: May seek movement or stimulation
  • Developmental Delay: Not always present
Important: It’s Not Always One or the Other

Children can have:
  • Autism AND ADHD
  • Developmental delays alongside other conditions
This is why assessment looks at the whole picture, not just one behaviour.
What If I’m Still Not Sure?

That’s completely normal.
Most parents don’t start with clarity, they start with noticing something is different.
Start here:
Should I Get My Child Assessed?

You might consider an assessment if:
  • You’re noticing ongoing differences
  • Your child is struggling in daily activities
  • You feel unsure and want clarity
Learn more:
Can I Start Support Without a Diagnosis?

Yes.
You don’t need to wait for a diagnosis to begin helping your child.
Support can focus on:
  • Communication
  • Emotional regulation
  • Behaviour
  • Daily routines
Learn more:
A Simple Way to Think About It
​
  • Autism → Differences in communication, social understanding, and sensory processing
  • ADHD → Differences in attention, impulse control, and activity levels
  • Developmental Delay → Slower development of skills

But remember: Every child is unique, and overlap is common
You Don’t Have to Work This Out Alone

If you’re trying to understand what’s going on for your child, it’s okay to ask for help.

At Belong Health, we support families across Perth and Mandurah in understanding their child’s development and next steps.
Not Sure What the Next Step Is?

​That’s completely okay.

Book a free 20-minute call with our team
Or contact us to talk through your situation
Our team is here to help call us on 08 9586 3934 or send us an email here

Have a question? or need more information

Our friendly team are happy to help call us on 08 9586 3934 or send us a message

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Frequently Asked Questions - Autism vs ADHD vs Developmental Delay

What is the difference between Autism, ADHD, and Developmental Delay?
​Autism, ADHD, and Developmental Delay are different developmental conditions, although some characteristics can overlap.
Autism typically involves differences in social communication, sensory processing, routines, interests, and social interaction.
ADHD primarily affects attention, impulse control, activity levels, executive functioning, and emotional regulation.
Developmental Delay refers to a child developing skills more slowly than expected in one or more areas such as communication, motor skills, social development, or learning.
A comprehensive assessment can help determine which factors may be contributing to a child's presentation.

Can ADHD look like autism?
Yes.
Some characteristics of ADHD and autism can overlap, including:
  • Social difficulties
  • Emotional regulation challenges
  • Sensory sensitivities
  • Difficulties with attention
  • Executive functioning differences
However, autism and ADHD are separate neurodevelopmental conditions with different diagnostic criteria.

Can autism be mistaken for ADHD?
Sometimes.
Because some characteristics overlap, children may initially appear to fit one profile before further assessment identifies autism, ADHD, or both.
This is one reason why comprehensive assessment can be valuable.

Can a child have both Autism and ADHD?
Yes.
Many children are both autistic and ADHD.
Research shows there is significant overlap between the two conditions, and it is common for both to occur together.

Which is more serious: Autism, ADHD, or Developmental Delay?
None of these conditions are inherently more serious than the others.
The impact depends on the individual child's strengths, support needs, environment, and daily functioning.
Every child experiences these conditions differently.

What are some early signs of autism?
Some early signs may include:
  • Differences in social interaction
  • Reduced response to name
  • Delayed gestures such as pointing
  • Repetitive behaviours
  • Sensory sensitivities
  • Strong preference for routines
  • Differences in communication development
Autism presents differently from person to person.

What are some early signs of ADHD?
Early signs of ADHD may include:
  • High levels of movement
  • Difficulty sustaining attention
  • Impulsivity
  • Frequent interruptions
  • Difficulty waiting
  • Forgetfulness
  • Emotional regulation challenges
These behaviours must be considered in the context of the child's age and development.

What are some signs of developmental delay?
Developmental delays may affect:
  • Communication
  • Motor skills
  • Learning
  • Social development
  • Daily living skills
Signs vary depending on which developmental areas are affected.

Can developmental delay look like autism?
Sometimes.
Children with developmental delays may experience communication, social, or behavioural differences that can appear similar to autism.
Assessment helps determine the underlying reasons for a child's presentation.

Can developmental delay look like ADHD?
Yes.
Children experiencing developmental delays may have difficulties with attention, emotional regulation, learning, or participation that can resemble ADHD traits.
Comprehensive assessment helps clarify these differences.

Can speech delay occur without autism?
Absolutely.
Speech and language delays can occur for many reasons and do not automatically indicate autism.
Many children with speech delays are not autistic.
A Speech Pathology assessment can help identify communication strengths and support needs.

What are developmental milestones?
Developmental milestones are skills that children commonly develop within particular age ranges.
Milestones may relate to:
  • Communication
  • Social interaction
  • Motor skills
  • Play
  • Learning
  • Independence
Every child develops at their own pace.

What are developmental red flags?
Some developmental red flags may include:
  • Significant delays in communication
  • Loss of previously acquired skills
  • Limited social engagement
  • Difficulty responding to people
  • Delays across multiple developmental areas
Further assessment may be helpful if concerns arise.

Can children outgrow developmental delays?
Some children catch up to their peers over time, while others may continue to require support.
The outcome depends on the nature and cause of the developmental delay.
Early identification and support can help maximise participation and skill development.

How do professionals determine whether it is Autism, ADHD, or Developmental Delay?
Assessment may include:
  • Parent interviews
  • Developmental history
  • Questionnaires
  • Clinical observations
  • Standardised assessments
  • School or childcare feedback
Clinicians consider the child's overall developmental profile rather than relying on one behaviour alone.

When should I seek an assessment?
You may wish to consider assessment if your child experiences:
  • Communication delays
  • Social difficulties
  • Emotional regulation challenges
  • Learning difficulties
  • Attention concerns
  • Developmental differences
  • Difficulties participating in everyday activities
Assessment can help identify strengths, support needs, and appropriate next steps.

Can children receive support before a diagnosis?
​Yes.
Many children access Occupational Therapy, Speech Pathology, Psychology, Counselling, Positive Behaviour Support, and developmental support services before receiving a formal diagnosis.
Support is often based on functional needs rather than diagnosis alone.

Can autism, ADHD, and developmental delay occur together?
Yes.
Some children may experience more than one developmental condition.
Assessment helps identify the child's individual strengths, support needs, and areas requiring support.

What happens if my child is assessed and does not meet criteria for Autism or ADHD?
Assessment can still provide valuable information.
The process may identify:
  • Developmental delays
  • Learning difficulties
  • Communication disorders
  • Sensory processing differences
  • Emotional or behavioural support needs
This information can help guide appropriate intervention and support planning.
Related Autism Resources
​
If you're unsure whether your child's challenges may relate to Autism, ADHD, or Developmental Delay, these resources may also be helpful:
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