Learn the key differences between autism and ADHD, including signs, ASD levels, GDD, and developmental milestones. A comprehensive guide for families navigating these conditions.
Estimated reading time: 9 minutes
If you're a parent or grandparent, you've probably heard the terms autism and ADHD more and more in conversations at schools, playgrounds, or doctor's visits. Both conditions are now widely recognised, and yet they're often confused. I've sat with other parents who say things like:
"My grandson has ADHD, but isn't it similar to autism?"
"My daughter's teacher thinks she has ASD Level 2, but I thought that was the same as ADHD."
These misunderstandings are common. While autism and ADHD share some overlapping traits—like difficulties with attention, social interaction, or impulse control—they are distinct conditions, each with their own challenges and strengths.
In this article, we'll unpack the key differences between autism and ADHD, how ASD levels (1–3) help describe autism, and why concepts like GDD (Global Developmental Delay) and developmental milestones in the EYLF are important when understanding your child's journey.
Autism Spectrum Disorder (ASD) is a neurodevelopmental condition affecting communication, behaviour, and social interaction. Signs are usually noticeable in early childhood, though the degree of support needed varies widely.
The term spectrum reflects this diversity. Some children may only need gentle nudges in social learning (Level 1 autism), while others may require substantial or very substantial support (ASD level 2 or ASD level 3) across communication, daily living, and learning (American Psychiatric Association, 2013).
Attention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental condition primarily characterised by difficulties with attention, impulse control, and regulation of activity levels (CDC, 2022).
Unlike autism, ADHD is less about social communication differences and more about regulation—sustaining focus, controlling impulses, and moderating energy. ADHD often becomes noticeable once children start school, where demands for sitting still and concentrating become greater.
Autism is often described using levels of support:
e.g., difficulty in social cues, but communicates verbally.
Noticeable language and behavioural challenges.
Minimal speech, reliance on strict routines.
These levels of autism help professionals tailor support but do not predict potential. With the right environment, many children exceed expectations (Lord et al., 2020).
ADHD is generally divided into three presentations (APA, 2013):
Forgetful, easily distracted, struggles with sustained tasks.
Restless, talkative, impulsive.
A mix of both inattentive and hyperactive-impulsive traits.
Unlike autism, ADHD does not involve restricted/repetitive behaviours or differences in social reciprocity. But it often co-occurs with learning difficulties or emotional regulation challenges.
Here's a simple way to frame it:
Primarily about social communication differences and repetitive/restricted behaviours. ASD levels (1–3) reflect the amount of support needed.
Primarily about attention, impulse control, and activity regulation. Support varies, but there are no "levels" of ADHD like with autism.
Autism changes how a child connects with the world, while ADHD changes how a child regulates themselves in the world.
Families often ask whether missed developmental milestones automatically signal autism or ADHD. The truth is, it depends.
Some toddlers miss milestones across multiple domains (motor, speech, social). This may later lead to an ASD diagnosis, but not always (Shevell et al., 2003).
In Australia, educators use EYLF to track milestones like language, play, and problem-solving. This helps flag when a child may benefit from extra assessment.
Understanding these frameworks helps parents avoid panic while still seeking timely professional support.
Connect with qualified professionals who can help assess and support children with autism or ADHD.
A: Yes, research suggests around 30–50% of autistic individuals also meet criteria for ADHD (Leitner, 2014).
A: Autism is often diagnosed before age 3. ADHD is typically recognised once school starts.
A: Neither condition is outgrown, but support strategies can help children thrive.
A: No, support needs (Level 1, ASD Level 2, ASD Level 3) may shift with intervention and development.
A: Yes, but differently. Autism affects communication and social reciprocity; ADHD more often affects regulation and executive skills.