let loose vs let go of

let loose and let go of both are verbs.

Word	Noun	Adjective	Verb	Adverb
let loose	No	No	Yes	No
let go of	No	No	Yes	No

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

Other hypernyms of let loose include let go, release, relinquish.

let loose (verb)	let go of (verb)
express audibly; utter sounds (not necessarily words)	release, as from one's grip
turn loose or free from restraint