1) "Assault Rifle": An intermediate caliber, select-fire weapon (capable of both semi- and fully-automatic fire) designed to replace both rifles and submachine guns in the hands of troops.
2) "Assault Weapon": A legal term applied by the justice department in 1989 by executive decree to certain imported semiautomatic firearms with a combination of scary-looking features. In 1994 the definition was expanded to include certain domestically-made guns, but that was again dropped in 2004 after the sunset of the AWB. Ironically, the term "Pre-ban assault weapon" is an oxymoron, since by definition an "Assault Weapon" is a weapon with X combination of features that was built after the ban took effect.
That is all.