Status-quo means the existing state of something. A common example used for this is like saying a rich person is happy with their status-quo. They are happy with how things are going.
Avant-garde means a couple of different things depending on if you use it as a noun, verb, adjective, etc. It basically refers to ideas or proposals that are extremely creative, innovative. A good way to think of this word is the expression "think out of the box." Avant-garde ideas are NOT common or plain.
