Septet and Sevens

Septet noun - A musical composition written for seven performers.

Sevens is a synonym for septet. In some cases you can replace term "Sevens" with "Septet", this nouns are similar.

Sevens noun - A card game in which you play your sevens and other cards in sequence in the same suit as the sevens; you win if you are the first to use all your cards.

Septet is a synonym for sevens. You can use "Septet" instead a noun "Sevens".