afterward vs subsequently

afterward and subsequently both are adverbs.

Word	Noun	Adjective	Verb	Adverb
afterward	No	No	No	Yes
subsequently	No	No	No	Yes

As adverbs, afterward and subsequently are synonyms defined as:

afterward and subsequently: happening at a time subsequent to a reference time

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

afterward (adverb)	subsequently (adverb)
happening at a time subsequent to a reference time	happening at a time subsequent to a reference time