burdensomeness vs heaviness

burdensomeness and heaviness both are nouns.

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

As nouns, burdensomeness and heaviness are synonyms defined as:

Other synonyms of burdensomeness include onerousness, oppressiveness.

burdensomeness (noun)	heaviness (noun)
unwelcome burdensome difficulty	the property of being comparatively great in weight
	used of a line or mark
	unwelcome burdensome difficulty
	an oppressive quality that is laborious and solemn and lacks grace or fluency
	persisting sadness