A wight is a reanimated corpse, either human or animal, raised from death by the use of necromancy. Wights raised by the White Walkers were often referred to collectively as the Army of the Dead

White Walkers are sentient inhuman beings capable of magic and turning dead people into zombies that do their bidding. Those zombies are then called wights

A wight was a member of the army of the dead and fought in the Battle of Winterfell. He was killed at some point during the conflict beyond the Wall or Great War and resurrected