harshness vs gruffness

harshness and gruffness both are nouns.

Word	Noun	Adjective	Verb	Adverb
harshness	Yes	No	No	No
gruffness	Yes	No	No	No

As nouns, gruffness is a hyponym of harshness; that is, gruffness is a word with a more specific, narrower meaning than harshness:

Other hyponyms of harshness include hoarseness, huskiness.

harshness (noun)	gruffness (noun)
the quality of being harsh or rough or grating to the senses	a throaty harshness
excessive sternness	an abrupt discourteous manner
the roughness of a substance that causes abrasions
the quality of being cruel and causing tension or annoyance