Is the "Rifle Bolt Safety" on the M-16A1 called a Forward Assist as another name, or are these two different?

2 different sources might be referring to the same improvement made upon the M16 in the M16A1

The bolt has a series of grooves cut into the right hand side.
The foreward assist is just a spring loaded pin with wide flat end that the shooter can strike several times to force the bolt forward. The pin pushes on the bolt's grooves in a forward motion so the bolt chambers and locks.
The M16A1 first saw this improvement, among other improvements like a better flash supressor and a chromed bore.
The misfire procedure for the M16A1 is known by the acronym SPORTS. Slap up on the bottom of the magazine,
Pull the charging handle to the rear, Release the charging handle, Tap the foreward assist, Shoot the target.

The 'forward assist' on the M16 series rifles is intended to help chamber a cartridge in the rifle if there is a jam. The rifle is made to very close tolerances and can jam if dust or dirt get into it. The forward assist will provide the extra push to get the round to fully chamber.

the improvements made on the M-16A1 over the M-16 were:

forward assist
Brass deflector
Flash suppressor
rear and forward sights

I think what your referring to is the rear locking safety. that is what happens when the last round is fired. the bolt locks to the rear so you can place the magazine in and hit the bolt release and fire away again. Hope this helps, it was from memory.