expression vs outburst

expression and outburst both are nouns.

Word	Noun	Adjective	Verb	Adverb
expression	Yes	No	No	No
outburst	Yes	No	No	No

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

Other hyponyms of expression include lamentation, mourning, act, blowup, ebullition, effusion, gush.

expression (noun)	outburst (noun)
the act of forcing something out by squeezing or pressing	a sudden violent disturbance
the feelings expressed on a person's face	an unrestrained expression of emotion
a word or phrase that particular people use in particular situations	a sudden intense happening
the style of expressing yourself
expression without words
a group of symbols that make a mathematical statement
the communication (in speech or writing) of your beliefs or opinions
a group of words that form a constituent of a sentence and are considered as a single unit
(genetics) the process of expressing a gene