soothe vs quieten

soothe and quieten both are verbs.

Word	Noun	Adjective	Verb	Adverb
soothe	No	No	Yes	No
quieten	No	No	Yes	No

As verbs, quieten is a hyponym of soothe; that is, quieten is a word with a more specific, narrower meaning than soothe:

Other hyponyms of soothe include calm, calm down, lull, quiet, still, tranquilize, tranquillise, tranquillize, allay, ease, relieve, still.

soothe (verb)	quieten (verb)
cause to feel better	cause to be quiet or not talk
give moral or emotional strength to	make calm or still
	become quiet or quieter