alluvial deposit vs alluvium

alluvial deposit and alluvium both are nouns.

Word	Noun	Adjective	Verb	Adverb
alluvial deposit	Yes	No	No	No
alluvium	Yes	No	No	No

As nouns, alluvial deposit and alluvium are synonyms defined as:

alluvial deposit and alluvium: clay or silt or gravel carried by rushing streams and deposited where the stream slows down

Other synonyms of alluvial deposit include alluvial sediment, alluvion.

alluvial deposit (noun)	alluvium (noun)
clay or silt or gravel carried by rushing streams and deposited where the stream slows down	clay or silt or gravel carried by rushing streams and deposited where the stream slows down