Even though Social Security is a Federal program, the initial decisions are made at local state offices. It really boils down to which Disability Determination Agent you get. They have common standards they have to meet, but after that, I'm not sure what the difference is.

Here's a little more information on the process:
http://www.ssa.gov/disability/determination.htm

If you google "disability determination service" and your state, you should be able to locate the office in your area. Tread very lightly in contacting them, though. They are human and don't appreciate feeling badgered. The agent I was in contact with in my state was very nice and moved things along as quickly as she could, but sometimes their hands are tied depending on what records need to be received.