loosen up vs decompress

loosen up and decompress both are verbs.

Word	Noun	Adjective	Verb	Adverb
loosen up	No	No	Yes	No
decompress	No	No	Yes	No

As verbs, loosen up and decompress are synonyms defined as:

Other synonyms of loosen up include relax, slow down, unbend, unwind.

loosen up (verb)	decompress (verb)
become less tense, rest, or take one's ease	become less tense, rest, or take one's ease
cause to feel relaxed	decrease the pressure of
make one's body limber or suppler by stretching, as if to prepare for strenuous physical activity	restore to its uncompressed form
cause to become unblocked
become less tense, less formal, or less restrained, and assume a friendlier manner