It's just a fork. Zwischenzug is when you make an move in the middle of a tactical combination or right before winning some kind of material. For example, if your opponent's queen is hanging, and your knight is also hanging, you might move the knight to safety with a check, and then take the queen, instead of taking the queen immediately. This article has more info about it:
https://www.chess.com/terms/zwischenzug-chess
Sometimes I will move a piece in order to put the opponent in check, forcing them to react. After they block my attack, I will then use the new position of my piece to launch an attack on a now undefended piece. Is this zwischenzug, or is this just forking the opponent with a forced move attached?