American blends or toasted blends as they used to be known are used in cigarette styles like Marlboro consisting of mainly virginia and burley tobaccos, with some oriental mixed in some blends.
English blends are generally made up of just virginia tobacco, and tend to be a lighter smoke then the chinese higher nicotine blends. Mainly used in cigarette styles like Kent.
Chinese blends are generally made up of virginia tobacco, and tend to be a harsher smoke then the english blend, and is higher in nicotine. Used in cigarette styles like Chunghwa.