ground attack vs onrush

ground attack and onrush both are nouns.

Word	Noun	Adjective	Verb	Adverb
ground attack	Yes	No	No	No
onrush	Yes	No	No	No

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

Other hypernyms of ground attack include attack, onset, onslaught.

ground attack (noun)	onrush (noun)
an attack by ground troops	(military) an offensive against an enemy (using weapons)
	a forceful forward rush or flow