fall back vs retire

fall back and retire both are verbs.

Word	Noun	Adjective	Verb	Adverb
fall back	No	No	Yes	No
retire	No	No	Yes	No

As verbs, retire is a hypernym of fall back; that is, retire is a word with a broader meaning than fall back:

Other hypernyms of fall back include draw back, move back, pull away, pull back, recede, retreat, withdraw.

fall back (verb)	retire (verb)
go back to bad behavior	prepare for sleep
retreat	cause to get out
hang (back) or fall (behind) in movement, progress, development, etc.	cause to be out on a fielding play
fall backwards and down	lose interest
move back and away from	pull back or move away or backward
have recourse to	dispose of (something no longer useful or needed)
	break from a meeting or gathering
	go into retirement; stop performing one's work or withdraw from one's position
	withdraw from active participation
	make (someone) retire
	withdraw from circulation or from the market, as of bills, shares, and bonds