In Warzone 2100, there are 2 different kinds of armor in-game: kinetic armor (protection against ballistic impacts and such), and thermal armor (protection against heat or energy weapons). Depending on the weapon used, damage would be subtracted by either the target's kinetic armor or the target's thermal armor.
While some bodies may have higher kinetic armor than thermal armor, or vice-versa, keep in mind that weapon modifiers often have a bigger effect on damage than armor does. For example, despite having poor thermal armor, Collective bodies mounted on Tracks are resistant towards anti-personnel lasers, despite them dealing thermal damage.
See Also: Damage Formula