let down vs depress

let down and depress both are verbs.

Word	Noun	Adjective	Verb	Adverb
let down	No	No	Yes	No
depress	No	No	Yes	No

As verbs, depress is a hyponym of let down; that is, depress is a word with a more specific, narrower meaning than let down:

Other hyponyms of let down include reef, dip, incline.

let down (verb)	depress (verb)
fail to meet the hopes or expectations of	lessen the activity or force of
move something or somebody to a lower position	press down
	cause to drop or sink
	lower someone's spirits; make downhearted
	lower (prices or markets)