asperity vs severity

asperity and severity both are nouns.

Word	Noun	Adjective	Verb	Adverb
asperity	Yes	No	No	No
severity	Yes	No	No	No

As nouns, asperity and severity are synonyms defined as:

Other synonyms of asperity include grimness, hardship, rigor, rigorousness, rigour, rigourousness, severeness.

asperity (noun)	severity (noun)
something hard to endure	excessive sternness
harshness of manner	used of the degree of something undesirable e.g. pain or weather
	something hard to endure
	extreme plainness