morale booster vs boost

morale booster and boost both are nouns.

Word	Noun	Adjective	Verb	Adverb
morale booster	Yes	No	No	No
boost	Yes	No	Yes	No

As nouns, boost is a hypernym of morale booster; that is, boost is a word with a broader meaning than morale booster:

Other hypernyms of morale booster include encouragement.

morale booster (noun)	boost (noun)
anything that serves to increase morale	the act of giving hope or support to someone
	the act of giving a push
	an increase in cost

morale booster (verb)	boost (verb)
	increase or raise
	give a boost to; be beneficial to
	push or shove upward, as if from below or behind
	increase
	contribute to the progress or growth of