stack away vs stash away

stack away and stash away both are verbs.

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

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

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

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