blitzkrieg vs onslaught

blitzkrieg and onslaught both are nouns.

Word	Noun	Adjective	Verb	Adverb
blitzkrieg	Yes	No	Yes	No
onslaught	Yes	No	No	No

As nouns, onslaught is a hypernym of blitzkrieg; that is, onslaught is a word with a broader meaning than blitzkrieg:

blitzkrieg: a swift and violent military offensive with intensive aerial bombardment
onslaught: (military) an offensive against an enemy (using weapons)

Other hypernyms of blitzkrieg include attack, onrush, onset.

blitzkrieg (noun)	onslaught (noun)
a swift and violent military offensive with intensive aerial bombardment	(military) an offensive against an enemy (using weapons)
	the rapid and continuous delivery of linguistic communication (spoken or written)
	a sudden and severe onset of trouble

blitzkrieg (verb)	onslaught (verb)
fight a quick and surprising war