evening vs guest night

evening and guest night both are nouns.

Word	Noun	Adjective	Verb	Adverb
evening	Yes	No	No	No
guest night	Yes	No	No	No

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

evening: the latter part of the day (the period of decreasing daylight from late afternoon until nightfall)
guest night: an evening when members of a club or college can bring their friends as guests

evening (noun)	guest night (noun)
the latter part of the day (the period of decreasing daylight from late afternoon until nightfall)	an evening when members of a club or college can bring their friends as guests
a later concluding time period
the early part of night (from dinner until bedtime) spent in a special way