Hello

meds can have an effect on this if you are currently on any. from my family and my own personal experience, it seems that there is a slight difference in the two. i dont know how to explain it tho. with me, my intense interests are pretty small (such as rock collecting, organizing cards(solitaire most recently), swirly like items that are in an never ending twisty like shape, video games, and computer.) but they do rotate. not as often as they used to (maybe age played a part in that), but thats been my rotation pretty much since i was a toddler (and im 28yrs old now lol). i too, am autistic. and in my experience the adhd meds react differently in those on the autism spectrum, than they do with those with ADHD.
the two also share a common issue with the sensory processing difficulties.
as a kid the adhd meds made me cry as soon as they kicked in, i recently was finally able to find the words to explain why- giving a overstimulated/overwhelmed child on the brink of a meltdown, something that makes them focus even more (instead of trying to come by unintentionally zoning out), equals a very rough day, for both child and parents(and anyone else involved). sometimes now i still have that issue, but the med is much more helpful now, than when they kept trying since i was young..- oh! something my first pdoc told my parents after evaluating me was that he was having a hard time deciding if i was adhd or autism. he ended up going with autism and told my parents that one main reason why was because when he explained indepth what was expected of me, then i would do it, (such as sitting still while the second hand on the clock went all the way back up to the top.) but when he just told me to sit still for as long as i could, i moved within the first 5 seconds. infact the second time i was determined to go even further with sitting still [emoji15] and had a meltdown-ish as he took the clock back up and i didnt like being intereupted from the task.

but also no two people with autism are exactly alike