It legitimately doesn't. Assault rifle has a set definition, it's a rifle with a detachable magazine which fires a intermediate round and have select fire capability.
Assault weapon is defined most colloquially as a semi auto rifle which fires a intermediate cartridge and a detachable magazine which has X features. Where X is largely cosmetic features which do not change the lethality of the rifle. X also varies by state. Examples of X include but are not limited to barrel shrouds, collapsible stock, threaded barrels etc.
Assault rifles were banned for civilian manufacture after 1986 and only one person ever has been killed by a assault rifle after 1986. Assault weapons were banned from 94-04 and in certain states.
In fact there are documents in Congress records which state the name was chosen because it was confusing to those not educated in firearms to build support for the original assault weapon ban Circa 1993.
So not semantics.