The answer is they are not but it’s more about proximity and shared experience. No two neurodivergent people are the same and those with different divergences sometimes horribly clash in terms of communication styles. However two autistic people may have more in common in terms of communication styles and shared experience to communicate far more easily than with a neurotypical person.
This is actually a well studied phenomenon in research as autistic people have been shown not to have worse social communication or empathy but differently structured kinds that are sometimes incompatible with neurotypical people (I’d go find some papers but im typically this from bed in the morning)
Also if you’re looking for resources on how to best support and work with neurodivergent people I highly suggest you pick up The Canary Code by Dr. Ludmila Praslova, it’s probably the best text on the subject to date: https://www.penguinrandomhouse.com/books/742858/the-canary-code-by-ludmila-n-praslova-phd/