Haha :) At least you asked about these things instead of just pretending you know like my dad does! He knows probably less than you but the ignorance brings into him trying to say things and making himself sound like an a**. I commend you for your curiosity!
EDIT: Amp, we posted at the same time again. XD A Tom thumb is not a snaffle mainly because it has shanks. A snaffle refers to a non-leverage bit, not just a jointed mouthpiece. A snaffle can be a snaffle an have differance types of mouthpieces so long as there is no leverage.