break into vs let loose

break into and let loose both are verbs.

Word	Noun	Adjective	Verb	Adverb
break into	No	No	Yes	No
let loose	No	No	Yes	No

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

Other hypernyms of break into include emit, let out, utter.

break into (verb)	let loose (verb)
change pace	express audibly; utter sounds (not necessarily words)
express or utter spontaneously	turn loose or free from restraint