The media have been playing this game for 25 years now.
An assault rifle is an intermediate caliber select fire rifle or carbine. A battle rifle is a select fire full power rifle.
An assault weapon, is whatever sort of gun, including pistols and shotguns, they want to ban.. this year. Current definition includes semiautomatic, with "anything which can function as a grip, + removable magazine or fixed magazine with >10 rounds capacity. Next year the details will differ. Although they may change tactics and go after "sniper rifles", once they get the semi-automatics.