night life vs amusement

night life and amusement both are nouns.

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

As nouns, amusement is a hypernym of night life; that is, amusement is a word with a broader meaning than night life:

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

Other hypernyms of night life include entertainment.

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