peep vs let out

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

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

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

Other hypernyms of peep include emit, let loose, utter.

peep (noun)	let out (noun)
a secret look
the short weak cry of a young bird

peep (verb)	let out (verb)
appear as though from hiding	make (clothes) larger
make high-pitched sounds	make known to the public information that was previously known only to a few people or that was meant to be kept a secret
speak in a hesitant and high-pitched tone of voice	express audibly; utter sounds (not necessarily words)
look furtively	bring out of a specific state
cause to come into view