Difference between Plaque and Plack

What is the difference between Plaque and Plack?

Plaque as a noun is any flat, thin piece of metal, clay, ivory, or the like, used for ornament, or for painting pictures upon, as a slab, plate, dish, or the like, hung upon a wall; also, a smaller decoration worn on the person, as a brooch. while Plack as a noun is any of various small coins used in scotland and the netherlands during the 15th and 16th centuries, having a value in scotland of four pennies scots.

We hope you now know whether to use Plaque or Plack in your sentence.