Infantry-based anti-armor units are one of the bases of any army, with out these little plastic men with big guns. All other ABS composed ground units would have to run in fear of bigger faster and better armed units such as tanks, hover craft, and air units. Anti-armor units differ form army to army, unit to unit but almost all have some type of explosive device most of the time being projectile based.
It may also be pointed out that ammo is anther thing that separates anti-armor units form the reason of the normal infantry , for while rifle units have several rounds per clip. It is not at all uncommon for a anti-armor weapon to have only one round per clip resulting in the need for abnormal ammo transport such as packs or support troops to carry the ammo. This need for ammo makes anti-armor units much less flexible in battle in comparison to other infantry.