From what I understand there are two different social security disability SSDI which is what those who worked and then are later disabled get.
That's what I get and that's also what I heard at social security "You worked for this, you paid into that fund. It's your money you're getting back...."

The other one however is basically federal welfare for those unable to provide for themselves and who are not servicable through other disability programs (Workmans comp., V.A. etc...)

Hope this helps? (I am planning on just not telling them if I can help it.)