I know they are new (hard) letters to you, but P, B and T should not sound the same ever. The process of making P & B share some similarity (both have lips pinched to start with) but with P we expulse air forcefully and in B it's more effortless if you will. With T, the tongue is placed on the back of the front teeth and air is also forced out (but the lips are not pinched together, the mouth is open). I hope it helps.