somewhat vs slightly

somewhat and slightly both are adverbs.

Word	Noun	Adjective	Verb	Adverb
somewhat	No	No	No	Yes
slightly	No	No	No	Yes

As adverbs, somewhat and slightly are synonyms defined as:

Other synonyms of somewhat include more or less.

somewhat (adverb)	slightly (adverb)
to certain extent or degree	to a small degree or extent
to a small degree or extent	in a slim or slender manner