Neither are current models. The 7100t has been replaced by the 7105t (better screen and beyboard). The 7100g has been replaced by the 7130c.
Internally, the 7100g and t are identical - they have different shells and keyboards.
BlackBerrys are more like smart e-mail devices. They do e-mail better than anything out there - but they really aren't "smart phones" like the Windows Mobile or PPC models. But they are MUCH more stable.
About 10 seconds before you posted i read about the 7105. So the 7100s do not have an OS. They are just heavily featured "normal" phones? What about this 7105? decent phone? will i enjoy it. I have about 150 to spend on a phone. and i am just looking for the best deal.
given my limitations what would you say was a better option? I had the razr, it was okay but not my style. i sold my razr (for a profit haha) and now i'm using my old sony ericson 637. I have 150ish to spend, i like the email, i text a good bit on my small phone so i'm sure i could get used to the suretext, or whatever else predictive text these use. so text, email, and a novelty program or two, no games really. can i load a GPS program on this phone or no?