evening vs period of time

evening and period of time both are nouns.

Word	Noun	Adjective	Verb	Adverb
evening	Yes	No	No	No
period of time	Yes	No	No	No

As nouns, period of time is a hypernym of evening; that is, period of time is a word with a broader meaning than evening:

Other hypernyms of evening include period, time period.

As nouns, period of time is a hypernym of evening; that is, period of time is a word with a broader meaning than evening:

evening: the early part of night (from dinner until bedtime) spent in a special way
period of time: an amount of time

Other hypernyms of evening include period, time period.

evening (noun)	period of time (noun)
the latter part of the day (the period of decreasing daylight from late afternoon until nightfall)	an amount of time
a later concluding time period
the early part of night (from dinner until bedtime) spent in a special way