stash away vs stack away

stash away and stack away both are verbs.

Word	Noun	Adjective	Verb	Adverb
stash away	No	No	Yes	No
stack away	No	No	Yes	No

As verbs, stash away and stack away are synonyms defined as:

Other synonyms of stash away include hive away, lay in, put in, salt away, store.

stash away (verb)	stack away (verb)
keep or lay aside for future use	keep or lay aside for future use