In Foxhole each weapon can deal a specific amount of damage, however how much of that damage is actually dealt to the target depends on the target's nature and its resistance to particular Damage Types.
Infantry
Soldiers receive the full damage amount regardless of the type.
The only exception is for Light Kinetic damage received at range when wearing an Armour Uniform (up to -33% damage for colonial uniform and up to -50% for the warden one when beyond 30m).
Vehicles
The damage a vehicle receives depends on the damage type and the vehicle's resistance type (unrelated to Tank Armor). All vehicles in a specific vehicle class (e.g. Armored Car) share the same resistance type.
Vehicle Tiers
Vehicles of a higher tier get an additional damage mitigation applied across the board regardless of damage type. After the resistance type mitigation is applied, the damage is reduced by 10% for Tier 2 and 20% for Tier 3. This is equivalent to Tier 2 having 11% more health, and Tier 3 25%. Prototype vehicles get a 25% damage increase. This additional resistance won't be taken into account in the resistance table below.
Structures
Each structures has a resistance type (not shown in-game) that defines how well it resists each damage type. With very few exceptions, structures are either highly resistant or immune to anti-tank weaponry 

and small arms fire 
, and they are always vulnerable to Demolition
damage. The structure resistance types mostly differ on how much they resist Explosive
, High Explosive
, Incendiary High Explosive
, and Heavy Kinetic
damage types.
Devastation
Additionally the devastation of the land a structure is on can increase the damage it receives across all damage types, virtually decreasing its maximum health. This effect won't be taken into account in the resistance table below.