As someone with a disability and having done a lot of voluntary work with disabled people, I always go on treating them the same, see the person not the disability unless assistance is obviously needed or asked for or it is raised by them.
In a professional situation it could come across badly, like the fact they are disabled makes you see them differently, maybe lesser, because of their disability.
Different but I used to get some comments (as a qualified solicitor) about the fact I looked really young, which to me gives undertones of are you experienced enough to help me, when I was.