onward vs forwards

onward and forwards both are adverbs.

Word	Noun	Adjective	Verb	Adverb
onward	No	No	No	Yes
forwards	No	No	No	Yes

As adverbs, onward and forwards are synonyms defined as:

Other synonyms of onward include ahead, forrader, forward, onwards.

onward (adverb)	forwards (adverb)
forward in time or order or degree	in a forward direction
in a forward direction	at or to or toward the front; forward