Statues were "three-dimensional work[s] of art, usually representing a person or animal, usually created by sculpting, carving, molding, or casting." Some statues in Nosgoth were animated through vampiric magic for various purposes. They appeared in Legacy of Kain: Defiance.
Guardian statues were once merely normal statues. However through vampiric magic have been animated for various purposes. Generally they are set as guardians of important places of objects. In their normal state they appear to be but normal statues, motionless and unreactive. However once the proper state set by the enchantment is triggered (i.e. a creature approaching a valuable artifact or attempting to enter a forbidden area) then the spell will take hold animating the one lifeless statue and transforming it into a powerful guardian. he form and function of guardian statues can vary from one type to another, but generally they can only be made vulnerable to attack at specific moments.