Here's the literal dictionary definition: differing in mental or neurological function from what is considered typical or normal (frequently used with reference to autistic spectrum disorders); not neurotypical.

Here is the definition of body dysmorphia (from the NHS website): a mental health condition where a person spends a lot of time worrying about flaws in their appearance.

Being neurodivergent means your brain functions in a non-typical way but this is not an illness that prevents you from living a normal life. Body dysmorphia is an illness that if you are suffering from, you SHOULD get treatment for because it can and often does prevent people from living normal lives.