rachitis vs redness

rachitis and redness both are nouns.

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

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

rachitis: inflammation of the vertebral column
redness: a response of body tissues to injury or irritation; characterized by pain and swelling and redness and heat

Other hypernyms of rachitis include inflammation, rubor.

rachitis (noun)	redness (noun)
childhood disease caused by deficiency of vitamin D and sunlight associated with impaired metabolism of calcium and phosphorus	red color or pigment; the chromatic color resembling the hue of blood
inflammation of the vertebral column	a response of body tissues to injury or irritation; characterized by pain and swelling and redness and heat