small beer vs triviality

small beer and triviality both are nouns.

Word	Noun	Adjective	Verb	Adverb
small beer	Yes	No	No	No
triviality	Yes	No	No	No

As nouns, small beer and triviality are synonyms defined as:

Other synonyms of small beer include trifle, trivia.

small beer (noun)	triviality (noun)
something of small importance	something of small importance
	the quality of being unimportant and petty or frivolous
	a detail that is considered insignificant