centre of curvature vs midpoint

centre of curvature and midpoint both are nouns.

Word	Noun	Adjective	Verb	Adverb
centre of curvature	Yes	No	No	No
midpoint	Yes	No	No	No

As nouns, midpoint is a hypernym of centre of curvature; that is, midpoint is a word with a broader meaning than centre of curvature:

centre of curvature: the center of the circle of curvature
midpoint: a point equidistant from the ends of a line or the extremities of a figure

Other hypernyms of centre of curvature include center, centre.

centre of curvature (noun)	midpoint (noun)
the center of the circle of curvature	a point equidistant from the ends of a line or the extremities of a figure