later on vs afterward

later on and afterward both are adverbs.

Word	Noun	Adjective	Verb	Adverb
later on	No	No	No	Yes
afterward	No	No	No	Yes

As adverbs, later on and afterward are synonyms defined as:

later on and afterward: happening at a time subsequent to a reference time

Other synonyms of later on include after, afterwards, later, subsequently.

later on (adverb)	afterward (adverb)
happening at a time subsequent to a reference time	happening at a time subsequent to a reference time