Ima do the lemmy thing and take this too seriously haha. neuro divergent covers everything that isn't neuro typical i.e. how society expects a brain to work. So the term covers not only ad(h)d and the autism spectrum but also things like ocd, trauma, (former) addiction, meditation masters, etc. saying there is a third thing next to neuro typical and neuro divergent is like saying there is a third thing next to pregnant and not pregnant

I can suggest a book by Nick Walker about this that was very enlightening for me: "Neuroqueer Heresies: Notes on the Neurodiversity Paradigm, Autistic Empowerment, and Postnormal Possibilities" I am also open to other Book recommendations