by choice vs on purpose

by choice and on purpose both are adverbs.

Word	Noun	Adjective	Verb	Adverb
by choice	No	No	No	Yes
on purpose	No	No	No	Yes

As adverbs, by choice and on purpose are synonyms defined as:

Other synonyms of by choice include advisedly, by design, deliberately, designedly, intentionally, purposely.

by choice (adverb)	on purpose (adverb)
with intention; in an intentional manner	with intention; in an intentional manner