Assault Rifle: A medium-caliber, select-fire shoulder weapon that bridges the roles between a machine pistol and a full-power bettle rifle.
Assault Weapon: A legislative term describing certain imported weapons that meet a list of defined cosmetic criteria. There were domestic "assault weapons" between 1994 and 2004, but the term no longer applies to anything but imported weapons, and is functionally meaningless outside a courtroom.
Assault Postcard: Mailed to your grandmother by her legislators and designed to scare her bloomers clean off with a combination of misleading photos, B.S. "definitions", and outright lies.