No extra abilities or speed, health tied to the level of the mission.
Vulnerable to Melee
Very large walker, moves slowly. Bodyshots are less effective than against other types of walker. Can take lots of shots before going down.
Vulnerable to Assault rifle
Slightly larger than Regular, with slightly slower movement. Their body armor soaks up a lot of damage, making them hard to takedown.
Vulnerable to Sniper rifle
Smaller size, faster movement. Amount of health is less than Regular.
Vulnerable to Pistol
Vulnerable to Shotgun
Vulnerable to SMG