The word phrase that is different in each set is the one that does not belong to the same category or group as the others. In the first set, "musician" is different because it is a profession, while the others are family relationships. In the second set, "factory" is different because it is a place, while the others are family relationships. In the third set, "often" is different because it is an adverb of frequency, while the others are adverbs of time. In the fourth set, "hour" is different because it is a unit of time, while the others are units of measurement.