extreme point vs apex

extreme point and apex both are nouns.

Word	Noun	Adjective	Verb	Adverb
extreme point	Yes	No	No	No
apex	Yes	No	No	No

As nouns, apex is a hyponym of extreme point; that is, apex is a word with a more specific, narrower meaning than extreme point:

Other hyponyms of extreme point include acme, peak, vertex.

extreme point (noun)	apex (noun)
the point located farthest from the middle of something	the highest point (of something)
	the point on the celestial sphere toward which the sun and solar system appear to be moving relative to the fixed stars