Major vs Minor Pieces
The rook and queen are called the “major pieces”, whereas the bishop and knights are called “minor pieces”. Pawns are not usually called pieces at all. The loss of a major piece (e.g. a rook) is usually enough to end the game, whereas the loss of a minor piece (worth 3 pawns) may often be overcome, especially if you’ve gotten a pawn or two for the minor piece.
Related Chess Tactics
Read more about these related chess strategies: