planation vs wearing away

planation and wearing away both are nouns.

Word	Noun	Adjective	Verb	Adverb
planation	Yes	No	No	No
wearing away	Yes	No	No	No

As nouns, wearing away is a hypernym of planation; that is, wearing away is a word with a broader meaning than planation:

planation: the process of erosion whereby a level surface is produced
wearing away: (geology) the mechanical process of wearing or grinding something down (as by particles washing over it), also figuratively

Other hypernyms of planation include eating away, eroding, erosion, wearing.

planation (noun)	wearing away (noun)
the process of erosion whereby a level surface is produced	(geology) the mechanical process of wearing or grinding something down (as by particles washing over it), also figuratively