peradventure vs mayhap

peradventure is a noun but mayhap is not a noun.

Word	Noun	Adjective	Verb	Adverb
peradventure	Yes	No	No	Yes
mayhap	No	No	No	Yes

As adverbs, peradventure and mayhap are synonyms defined as:

Other synonyms of peradventure include maybe, perchance, perhaps, possibly.

peradventure (noun)	mayhap (noun)
doubt or uncertainty as to whether something is the case

peradventure (adverb)	mayhap (adverb)
by chance	by chance