S.H.I.V. (Long War)
The main difference between vanilla and Long War S.H.I.V.s are that Long War allows S.H.I.V.s to be customized with up to three modules. Some are simple upgrades to health, magazine size, etc, others grant extra passive perks such as HEAT ammo or Opportunist. Some even grant new active abilities like Flush. Like vanilla, S.H.I.V.s have several Foundry projects to improve them as well.
S.H.I.V.s, like most mechanized units in Long War, have built-in damage reduction, which makes them a bit more durable, especially against light weapons.
When a S.H.I.V is destroyed, if you win the battle you will recover a S.H.I.V Chassis item, which can be used to rebuild the S.H.I.V at a lower cost than building a new one from scratch.