synovitis vs rubor

synovitis and rubor both are nouns.

Word	Noun	Adjective	Verb	Adverb
synovitis	Yes	No	No	No
rubor	Yes	No	No	No

As nouns, rubor is a hypernym of synovitis; that is, rubor is a word with a broader meaning than synovitis:

synovitis: inflammation of the synovial membrane that lines a synovial joint; results in pain and swelling
rubor: a response of body tissues to injury or irritation; characterized by pain and swelling and redness and heat

Other hypernyms of synovitis include inflammation, redness.

synovitis (noun)	rubor (noun)
inflammation of the synovial membrane that lines a synovial joint; results in pain and swelling	a response of body tissues to injury or irritation; characterized by pain and swelling and redness and heat