tendinitis vs redness

tendinitis and redness both are nouns.

Word	Noun	Adjective	Verb	Adverb
tendinitis	Yes	No	No	No
redness	Yes	No	No	No

As nouns, redness is a hypernym of tendinitis; that is, redness is a word with a broader meaning than tendinitis:

tendinitis: inflammation of a tendon
redness: a response of body tissues to injury or irritation; characterized by pain and swelling and redness and heat

Other hypernyms of tendinitis include inflammation, rubor.

tendinitis (noun)	redness (noun)
inflammation of a tendon	red color or pigment; the chromatic color resembling the hue of blood
	a response of body tissues to injury or irritation; characterized by pain and swelling and redness and heat