Anti-Material Rifle : a very large cartridge at the very limit of human ability to control, fired from a weapon that weighs more than twenty (and sometimes forty) pounds, capable of shooting armor-piercing and incendiary (and other) rounds, and reliable out to a mile in the hands of a trained individual.
Hunting Rifle: full size cartridges, long range, precise, with very high power, firing from a bolt. (Sniper rifles are hunting rifles with very precise tolerances, and high quality optics).
Battle Rifle: Full size cartridge, long distance, one round per trigger pull – necessary since the recoil is too large otherwise.
Assault Rifle: Intermediate Cartridge, medium distance, full auto. (Technically ‘select fire’.) Possible since by reducing the scale (force) of the cartridge the gun was controllable at full auto.
Semi Automatic Rifle: Intermediate cartridge. Firing a single round per trigger pull. It has turned out that full auto is useless other than for suppressing fire during movement. A skilled individual can fire american weapons (which have springs that dampen inertia) at pistol (fast) speeds without losing sight picture.
Sub machine gun: a pistol cartridge, and a high rate of fire, made possible by the use of a magazine, and requiring two hands. (600-800 rounds per minute, usually in short busts)
Modern 9mm semi-auto pistols with 15+ rounds have taken the market because they can be emptied (fired) quickly, effectively providing a low rate of fire submachine gun (180 rounds per minute) in a small package, while maintaining sight picture.
Modern 45 semi-auto pistols hold a smaller number of rounds and require a stronger individual to fire quickly, but are usually preferred by military special forces personnel.
Modern 10mm semi-auto pistols are hard to control for inexperienced smaller or weaker shooters, but can, if used properly stop a bear in the wild.
Modern large caliber revolvers can be used for hunting medium and large sized game. There are modern hunting pistols at the limit of human ability to control.
And we complete the loop and return to the hunting rifle.
Americans chose to make an ultra-light, full auto, sniper rifle with smaller cartridges so that they could carry more rounds (the M16/M4). Russians chose to make a full auto battle rifle regardless of weight (The AK). The Russian choice was superior in battlefield conditions.
It appears that the German technology (as usual) has found the optimum which is a heavier bullet but improving upon the black gun (ultra light weight) american weapon design. And this is the current direction of military weapons development.
It appears that the polymer pistol with octagonal barrel and fully replaceable trigger group has taken over the military handgun market.
Use the tool you can most comfortably master.