diversion vs onrush

diversion and onrush both are nouns.

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

As nouns, onrush is a hypernym of diversion; that is, onrush is a word with a broader meaning than diversion:

diversion: an attack calculated to draw enemy defense away from the point of the principal attack
onrush: (military) an offensive against an enemy (using weapons)

Other hypernyms of diversion include attack, onset, onslaught.

diversion (noun)	onrush (noun)
an activity that diverts or amuses or stimulates	(military) an offensive against an enemy (using weapons)
a turning aside (of your course or attention or concern)	a forceful forward rush or flow
an attack calculated to draw enemy defense away from the point of the principal attack