afterward vs afterwards

afterward and afterwards both are adverbs.

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

As adverbs, afterward and afterwards are synonyms defined as:

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

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

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