also vs besides

also and besides both are adverbs.

Word	Noun	Adjective	Verb	Adverb
also	No	No	No	Yes
besides	No	No	No	Yes

As adverbs, also and besides are synonyms defined as:

Other synonyms of also include as well, likewise, too.

also (adverb)	besides (adverb)
in addition	making an additional point; anyway
	in addition