Communication is key in relationships, which means the words you use when communicating matters a lot.
Criticism is communicating your concerns about an issue between you and your partner, which is aimed at making your partner look wrong or make them feel lesser than they are, which automatically puts them on the defensive.
Complaining is a better way of communicating your concerns to your partner without attaking them and getting to listen to you without putting up a fight.
Ravid Yosef of YourTango lists 3 smart ways couples can approach complaining without criticizing: