alluvion vs alluvial soil

alluvion and alluvial soil both are nouns.

Word	Noun	Adjective	Verb	Adverb
alluvion	Yes	No	No	No
alluvial soil	Yes	No	No	No

alluvion (noun)	alluvial soil (noun)
clay or silt or gravel carried by rushing streams and deposited where the stream slows down	a fine-grained fertile soil deposited by water flowing over flood plains or in river beds
the rising of a body of water and its overflowing onto normally dry land
gradual formation of new land, by recession of the sea or deposit of sediment