thermic fever vs heatstroke

thermic fever and heatstroke both are nouns.

Word	Noun	Adjective	Verb	Adverb
thermic fever	Yes	No	No	No
heatstroke	Yes	No	No	No

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

thermic fever: sudden prostration due to exposure to the sun or excessive heat
heatstroke: collapse caused by exposure to excessive heat

Other hypernyms of thermic fever include heat hyperpyrexia.

thermic fever (noun)	heatstroke (noun)
sudden prostration due to exposure to the sun or excessive heat	collapse caused by exposure to excessive heat