by vs aside

by is not a noun while aside is a noun.

Word	Noun	Adjective	Verb	Adverb
by	No	No	No	Yes
aside	Yes	No	No	Yes

As adverbs, by and aside are synonyms defined as:

Other synonyms of by include away.

by (noun)	aside (noun)
	a line spoken by an actor to the audience but not intended for others on the stage
	a message that departs from the main subject

by (adverb)	aside (adverb)
so as to pass a given point	on or to one side
in reserve; not for immediate use	out of the way (especially away from one's thoughts)
	in reserve; not for immediate use
	not taken into account or excluded from consideration
	placed or kept separate and distinct as for a purpose
	in a different direction