Part 1: Autism & ADHD -What They Are and How They Differ

There’s a lot of talk online about Autism vs ADHD, but the differences between Autism and ADHD can be subtle—especially for neurodivergent adults exploring a late diagnosis.

Let’s take a closer look at what Autism and ADHD are, how they differ, and the traits that make each unique. We’ll dive into overlap and co-occurrence in Part 2.

Laying the Foundation

Before we dive into the details, a few things to get us on the same page:

Language matters

Most Autistic adults prefer identity-first language, like “Autistic person” rather than “person with Autism.” Many also dislike the word “disorder,” though this varies for people, especially those with higher support needs. For ADHD, identity-first language is also common — “ADHDer” or “ADHer.”

I also use “traits” instead of “symptoms.” Why? Traits reflect natural variation in how neurodivergent brains experience the world, whereas “symptoms” implies something is broken.

Finally, keep in mind that diagnostic criteria focus on observable behaviors, not lived experience. People who don’t present “stereotypically” — including women, nonbinary folks, and culturally diverse individuals — are often missed or misdiagnosed.

What is Autism?

Autism is a neurodevelopmental difference, a type of innate neurodivergence. Key characteristics include:

• Differences in social communication and interaction (from neurotypical [NT] expectations)

• Pattern-oriented thinking

• Sensory processing differences: including picking up MORE of the sensory environment and therefore having sensory sensitivities, or the opposite - being less responsive to our senses (likely due to the way we pick up more of the environment), and sensory seeking behaviors.

• Variations in nervous system and brain wiring

• Focused or passionate interests

Other common traits:

• Stimming, echolalia, or creating systems/collections

• Routines and rituals, with discomfort at unexpected changes

• Special interests (SPINS), often involving deep dives into a topic

Traits must appear in early development, though they may be masked until social demands exceed an individual’s capacities. Challenges often arise not from the traits themselves but from navigating a world built for neurotypical people.

Sources: APA, 2022; Neff, 2022

What is ADHD?

ADHD is also a neurodevelopmental difference, and innate neurodivergence, involving differences in attention, energy regulation, and executive functioning.

There are three types:

1. Inattentive (ADHD-I) – difficulty sustaining attention, distractibility, forgetfulness, and disorganization

2. Hyperactive/Impulsive (ADHD-HI) – fidgeting, restlessness, interrupting, difficulty waiting

3. Combined (ADHD-C) – traits from both inattentive and hyperactive/impulsive types

ADHD traits begin in childhood (though may not present externally then) and affect social, academic, or occupational functioning. However, a person may mask their traits, or develop compensatory strategies to manage their ADHD, and may lead to diagnosis later in life (or no diagnosis or misdiagnosis). Like Autism, ADHD presents differently across contexts and individuals.

In the next section, we'll begin to explore how to tell the difference between Autism and ADHD.

Autism vs ADHD: Key Differences in Traits

If you’re exploring how Autism and ADHD show up in adults, understanding their differences and overlaps can help you approach your neurotype with clarity and self-compassion.

Next up in Part 2: Where we'll explore where these neurotypes overlap, co-occur, and why it matters.

Sound Familiar?

If you’re beginning to recognize yourself in some of these traits, you’re not alone. Understanding your neurotype(s) can bring clarity, self-compassion, and a deeper sense of belonging.

I offer neurodiversity-affirming therapy for Autistic and/or ADHDers ages six and older and adult Autism and ADHD assessments for folks seeking to understand themselves more fully.

You can learn more here:

Therapy

Assessments

Want more?

Dr. Megan Anna Neff, of Neurodivergent Insights provides a deeper dive into the DSM-V-TR criteria for Autism and ADHD, and a lot of the information from this series comes from their blog posts, and their research. Head here for their full blog post: DSM-5 Criteria for Autism Explained (In Picture Form), and here for their full blog post: DSM-5 Criteria for ADHD Explained (In Picture Form). They're also my #1 recommended resource.

FYI - If you are a past or current therapy or assessment participant - I have a license to share all their digital downloads.

References

American Psychiatric Association. (2022). Diagnostic and statistical manual of mental disorders (5th ed., text rev.).

Neff, M, A. (2022). DSM-5 criteria for Autism Explained (in picture form). Neurodivergent Insights. Retrieved October 24, 2025, from https://neurodivergentinsights.com/dsm-5-criteria-for-autism-explained-in-picture-form/

Neff, M, A. (2022). DSM-5 criteria for ADHD explained (in pictures). Neurodivergent Insights. Retrieved October 24, 2025, from https://neurodivergentinsights.com/dsm-5-criteria-for-adhd-explained-in-pictures/

Sokolova, E., Oerlemans, A. M., Rommelse, N. N. J., Groot, P., Hartman, C. A., Glennon, J. C., … & Buitelaar, J. K. (2017). A causal and mediation analysis of the comorbidity between attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). Journal of Autism and Developmental Disorders, 47(6), 1595–1604. https://doi.org/10.1007/s10803-017-3083-7