or else vs instead

or else and instead both are adverbs.

Word	Noun	Adjective	Verb	Adverb
or else	No	No	No	Yes
instead	No	No	No	Yes

As adverbs, or else and instead are synonyms defined as:

Other synonyms of or else include alternatively.

or else (adverb)	instead (adverb)
in place of, or as an alternative to	in place of, or as an alternative to
	on the contrary