amusement vs night life

amusement and night life both are nouns.

Word	Noun	Adjective	Verb	Adverb
amusement	Yes	No	No	No
night life	Yes	No	No	No

As nouns, night life is a hyponym of amusement; that is, night life is a word with a more specific, narrower meaning than amusement:

amusement: an activity that is diverting and that holds the attention
night life: the entertainment available to people seeking nighttime diversion

Other hyponyms of amusement include beguilement, distraction, edutainment, extravaganza, militainment, nightlife, show.

amusement (noun)	night life (noun)
an activity that is diverting and that holds the attention	the activity of people seeking nighttime diversion (as at the theater, a nightclub, etc.)
a feeling of delight at being entertained	the entertainment available to people seeking nighttime diversion