Do you want the definition of Assault rifle according to the Clinton scam/ban? Here goes: The awb (assault weapons ban) banned certain "militaristic" items. It also banned magazines that held more than 10 rounds. A rifle was considered an assault weapon if it had more than two of the following "evil" items: 1) Folding stock 2) Bayonet attachment 3) Pistol grip 4) Mount for grenade launcher 5) Flash suppressor 6) A removeable magazine that held more than 10 rounds So, by the above limited logic, a rifle can be an "assault rifle" without being a "battle rifle". A battle rifle would be an actual military rifle regardless of configuration.
Wait, I thought assault rifles means: intermediate cartridge, capable of semi or full auto, intermediate effective range, have a GPS system, a can opener...... A battle rifle? fires a more powerful rifle caliber cartridge that has better range and lethality, but which limits its accuracy and stability when firing at full-auto, so it's probably restricted to semi-automatic (garand) or a old fashion bolt-action (Mauser).
There aren't any formal 'right or wrong' definitions, but Liang has summarised the general current usage. Tony Williams: Military gun and ammunition website and Discussion forum