burdensomeness vs onerousness

burdensomeness and onerousness both are nouns.

Word	Noun	Adjective	Verb	Adverb
burdensomeness	Yes	No	No	No
onerousness	Yes	No	No	No

As nouns, burdensomeness and onerousness are synonyms defined as:

Other synonyms of burdensomeness include heaviness, oppressiveness.

burdensomeness (noun)	onerousness (noun)
unwelcome burdensome difficulty	unwelcome burdensome difficulty