blow vs let out

blow is a noun but let out is not a noun.

Word	Noun	Adjective	Verb	Adverb
blow	Yes	No	Yes	No
let out	No	No	Yes	No

As verbs, let out is a hypernym of blow; that is, let out is a word with a broader meaning than blow:

blow: cause to be revealed and jeopardized
let out: make known to the public information that was previously known only to a few people or that was meant to be kept a secret

Other hypernyms of blow include break, bring out, disclose, discover, divulge, expose, give away, let on, reveal, uncover, unwrap.

blow (noun)	let out (noun)
a powerful stroke with the fist or a weapon
forceful exhalation through the nose or mouth
street names for cocaine
an impact (as from a collision)
an unpleasant or disappointing surprise
an unfortunate happening that hinders or impedes; something that is thwarting or frustrating
a strong current of air

blow (verb)	let out (verb)
exhale hard	make (clothes) larger
free of obstruction by blowing air through	make known to the public information that was previously known only to a few people or that was meant to be kept a secret
melt, break, or become otherwise unusable	express audibly; utter sounds (not necessarily words)
burst suddenly	bring out of a specific state
shape by blowing
show off
cause to be revealed and jeopardized
allow to regain its breath
deposit eggs (of insects)
be in motion due to some air or water current
cause to move by means of an air current
leave; informal or rude
cause air to go in, on, or through
spout moist air from the blowhole
play or sound a wind instrument
make a sound as if blown
sound by having air expelled through a tube
provide sexual gratification through oral stimulation
spend lavishly or wastefully on
spend thoughtlessly; throw away
make a mess of, destroy or ruin
be inadequate or objectionable
be blowing or storming