What's the difference between backpiece and corselet?

Backpiece

Definition:

• (n.) Alt. of Backplate

Example Sentences:

Corselet

Definition:

• (n.) Armor for the body, as, the body breastplate and backpiece taken together; -- also, used for the entire suit of the day, including breastplate and backpiece, tasset and headpiece.
• (n.) The thorax of an insect.

Example Sentences: