What's the difference between BCT & AIT?

BCT is to teach you basic combat skills and get you in shape for military service. AIT is what teaches you your job. since you're signing as infantry you'll go to osut which is a combined basic and ait (since combat is your job). the basic training portion of osut will focus on the same things as every otehr basic, the ait portion will continue to focus on infantry tactics, advanced marksmanship, weapons, all that jazz if you get selected to be an 11B... if get selected to be an 11C, you'll spend your time learning about mortars.