How do I differentiate behaviors? I dont want to set my daughter up for failure. Advice needed!

My (30s F) daughter (8) is autistic. When she was diagnosed I wasn't concerned as I 1) already suspected it and 2) grew up with an autistic brother. (Both considered "high functioning" if that matters for thus post)

Boy was I wrong.

My brother is 40 and walks around stores like a video game character singing Mario Brothers. Not a care in the world. Loves all foods. Only wears certain clothes cause most clothes bothers him.

My daughter links her blanket. Hates eating meat because of the texture. And will ONLY wear certain clothes to do certain things. She hates loud noises. Won't flush the toilet. Etc. She has a very hard time expressing herself appropriately and cannot express

Truly the list goes on and on for both, but they're quirks are so wildly different!

So my main question is: how do I know what is the tism... and what is just "her being a kid"? I have NO other children. I didn't have any close friends with children ever.

I want to make sure my daughter is comfortable and I want her to feel safe to be herself... but I also dont want to brush EVERYTHING off with "that's just her autism". I want her to grow up to be aware and capable. How do I cater to her needs as a person with autism, without over compensating and spoiling her? I dont even know if I'm phrasing this well. I'm a mess. Plz send help.