erosion vs pitting

erosion and pitting both are nouns.

Word	Noun	Adjective	Verb	Adverb
erosion	Yes	No	No	No
pitting	Yes	No	No	No

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

erosion: erosion by chemical action
pitting: the formation of small pits in a surface as a consequence of corrosion

Other hyponyms of erosion include indentation, roughness, rust, rusting.

erosion (noun)	pitting (noun)
(geology) the mechanical process of wearing or grinding something down (as by particles washing over it), also figuratively	the formation of small pits in a surface as a consequence of corrosion
erosion by chemical action
a gradual decline of something
condition in which the earth's surface is worn away by the action of water and wind