express mirth vs laugh

express mirth is not a noun while laugh is a noun.

Word	Noun	Adjective	Verb	Adverb
express mirth	No	No	Yes	No
laugh	Yes	No	Yes	No

As verbs, express mirth and laugh are synonyms defined as:

Other synonyms of express mirth include express joy.

express mirth (noun)	laugh (noun)
	the sound of laughing
	a humorous anecdote or remark intended to provoke laughter
	a facial expression characteristic of a person laughing

express mirth (verb)	laugh (verb)
produce laughter	produce laughter