Each ride may have fastpass, single rider, and stand by lines but not necessarily all of those. Disabled guests get a piece of cardstock to show CMs that quickly and silently lets the CM know that the guest has a
limitation.
Disneyland has fewer options than WDW. WDW has autism, sun, cannot wait as in a neurovariant child, no stairs, vision, and hearing.
Guests in a wheelchair or other mobility aid are not supposed to need the GAC. At DLR all I have to do is point to my
ECV and they let me waddle onto rides but at DLR the lines are where they can see the ECV.
I have done a DLR list and Sue has a mega list of rides and how disabled guests can enter those rides. Some like Toy Story Mania are mainstreamed thus the disabled guest has to wait in line like everyone else. Some require using a special entrance and others through the exist. Read this board's FAQs to find out more.
Also what the GAC says the limitation is may affect where a guest is sent for a ride or show. Vision related GAC might be sent near the front, hearing might sit near speakers or in front of an ASL translator, and a wheelchair may sit in the back of a theater.
There is no front of the line pass and people are discouraged from implying that the GAC is an easy way to enter the rides. Yes, I have used a GAC to get to the head of the line and ride before other guests. I do however feel dirty and like I am cheating. I am sitting on my fat rump while they stand in the hot sun. I want to be normal and not get special treatment because I am in an ECV.
Make a Wish GACs are front of the line only if the child is medically fragile.