I've heard of them, yes. They're nothing I think about on a yearly basis, let alone a daily basis.

In a foxhunt the fox moves rapidly and randomly and makes as little sound as possible. With this test method, the fox does not move and its entire intention is to make the hound make noise in a particular way.

In a foxhunt the hounds move as rapidly as possible following the movements of the fox, and the hounds make a lot of noise. In this test mode the hound only makes noise when it is near the fox and that noise varies in loudness in direct relation to its proximity to the fox.

You don't want to see a further breakdown of the ways in which the fox and hound metaphor differ from a foxhunt.