That has to be awful. You and your brother are constantly getting compared to each other and it's probably hurting both of you, not to mention driving you apart. As brothers, you should be teaming up--helping each other--and your mom is doing nothing but telling him that he's inferior and irresponsible and etc., etc.
I don't know just how disabled your brother is. It's likely enough that he truly can't work. It's also likely that because of her constant putting him down, he's given up on finding work because she's convinced him that he's too lazy, too irresponsible, too disabled ever to make a go of it.
Next time she puts him down, stand up for him. He's your brother and he doesn't deserve this. She should be encouraging him. He knows he's unemployed; he knows he has problems socializing. He doesn't need to be told over and over, especially not in a way that makes it out to be a moral failure on his part. That kind of constant devaluation is nowhere near "constructive criticism" and is doing nothing to help. Tell your mom that you will NOT put up with being "the favorite child", that you consider your brother to be just as important as you are, and that you are not amused in the least by being preferred over him.
If you want to help your brother, that's probably your first step: Tell your mom to back off and stop nagging. I know; she's supposed to have the authority in the family; she's the mother. But sometimes the kids have to stand up to their parents, too, and this is one of those times. You could show your brother some of the useful things you know how to do, if you like; but don't focus on that too much. If my guess is right, he's been put down too often not to be pretty discouraged by now. He needs, most of all, a friend who likes him for himself, whether or not he's "lazy". You got common interests? Hang out with him. Do stuff together. Make a connection. He may or may not learn how to take better care of himself, but he'll certainly benefit from having somebody to hang out with who doesn't constantly judge him like his mom does.