expletive vs utterance

expletive and utterance both are nouns.

Word	Noun	Adjective	Verb	Adverb
expletive	Yes	No	No	No
utterance	Yes	No	No	No

As nouns, utterance is a hypernym of expletive; that is, utterance is a word with a broader meaning than expletive:

expletive: a word or phrase conveying no independent meaning but added to fill out a sentence or metrical line
utterance: the use of uttered sounds for auditory communication

Other hypernyms of expletive include vocalization.

expletive (noun)	utterance (noun)
profane or obscene expression usually of surprise or anger	the use of uttered sounds for auditory communication
a word or phrase conveying no independent meaning but added to fill out a sentence or metrical line