fever vs fervor

fever and fervor both are nouns.

Word	Noun	Adjective	Verb	Adverb
fever	Yes	No	No	No
fervor	Yes	No	No	No

As nouns, fervor is a hypernym of fever; that is, fervor is a word with a broader meaning than fever:

Other hypernyms of fever include excitation, excitement, fervour, inflammation.

fever (noun)	fervor (noun)
a state of nervous excitement	feelings of great warmth and intensity
a rise in the temperature of the body; frequently a symptom of infection	the state of being emotionally aroused and worked up