I can't see the difference between a waiting move and zugzwang.
Zugzwang is when one side would like to "pass" but cannot. With a waiting move, you essentially do "pass". A waiting move could lead to zugzwang if one side has the ability to play them and the other does not, but this is by no means necessary.
An opponent might have their own waiting moves (in which case the game could be drawn by repetition unless one side decides to do something meaningful) or they might have a different evaluation of the position and decide to simply proceed with their plan.
For example, one side might play a waiting move to see which side the opponent castles on, but the opponent may well think that the benefits of castling right then outweigh the drawbacks of giving the first player that information.