I am looking to buy a pitbull puppy and i was wondering what the bloodlines meant, if anything...?

what are the differences between gotty, razors edge, etc... i dont want a short stocky pit either... i want one with a fairly wide jaw, not short, lean, and brown with a white chest... what kind and type would that be? also, i was wondering if only females have the tighter faces.. i see a lot of males with sloppy and loose lips.. id like one with a tighter and more lean look..