let on vs sell someone out

let on and sell someone out both are verbs.

Word	Noun	Adjective	Verb	Adverb
let on	No	No	Yes	No
sell someone out	No	No	Yes	No

let on (verb)	sell someone out (verb)
make known to the public information that was previously known only to a few people or that was meant to be kept a secret	give information that compromises others