surge vs onrush

surge and onrush both are nouns.

Word	Noun	Adjective	Verb	Adverb
surge	Yes	No	Yes	No
onrush	Yes	No	No	No

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

Other hyponyms of surge include debris storm, debris surge.

surge (noun)	onrush (noun)
a sudden or abrupt strong increase	(military) an offensive against an enemy (using weapons)
a sudden forceful flow	a forceful forward rush or flow
a large sea wave

surge (verb)	onrush (verb)
see one's performance improve
rise rapidly
rise and move, as in waves or billows
rise or move forward
rise or heave upward under the influence of a natural force such as a wave