erosion vs rusting

erosion and rusting both are nouns.

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

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

erosion: erosion by chemical action
rusting: the formation of reddish-brown ferric oxides on iron by low-temperature oxidation in the presence of water

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

erosion (noun)	rusting (noun)
(geology) the mechanical process of wearing or grinding something down (as by particles washing over it), also figuratively	the formation of reddish-brown ferric oxides on iron by low-temperature oxidation in the presence of water
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