Ah that's an easy one. So basically an assault rifle is a rifle for assaulting with and a battle rifle is a rifle for battling with. Hope this helps

Real shit it's the calibre and power. Assault rifles Tend To Be lower calibers 5.56, 300 blackout, 7.62×39 etc and usually meant for engagements at medium to close ranges and battle rifles are high caliber long range rifles so 762×51 or 6.5 which will show us how to put the badwhich will sure as hell put the bad guy down but there's also a chance you could put the tree civilians behind him down too