daytime vs evening

daytime and evening both are nouns.

Word	Noun	Adjective	Verb	Adverb
daytime	Yes	No	No	No
evening	Yes	No	No	No

As nouns, evening is a hyponym of daytime; that is, evening is a word with a more specific, narrower meaning than daytime:

daytime: the time after sunrise and before sunset while it is light outside
evening: the latter part of the day (the period of decreasing daylight from late afternoon until nightfall)

Other hyponyms of daytime include afternoon, midafternoon, eve, even, eventide.

daytime (noun)	evening (noun)
the time after sunrise and before sunset while it is light outside	the latter part of the day (the period of decreasing daylight from late afternoon until nightfall)
	a later concluding time period
	the early part of night (from dinner until bedtime) spent in a special way