bending vs refraction

bending and refraction both are nouns.

Word	Noun	Adjective	Verb	Adverb
bending	Yes	No	No	No
refraction	Yes	No	No	No

As nouns, refraction is a hyponym of bending; that is, refraction is a word with a more specific, narrower meaning than bending:

Other hyponyms of bending include deflection, deflexion.

bending (noun)	refraction (noun)
the act of bending something	the amount by which a propagating wave is bent
the property of being bent or deflected	the change in direction of a propagating wave (light or sound) when passing from one medium to another
movement that causes the formation of a curve