Can you tell me the difference between an Attenuator/Blender ND filter and a Graduated one?

Q. Can you tell me the difference between an Attenuator/Blender ND filter and a Graduated one?

A. These are different terms for the same thing - some manufacturers use the term "attenuator/blender" (Tiffen) and others prefer to use the term "graduated" (Cokin, Lee).