alluvium vs delta

alluvium and delta both are nouns.

Word	Noun	Adjective	Verb	Adverb
alluvium	Yes	No	No	No
delta	Yes	No	No	No

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

alluvium: clay or silt or gravel carried by rushing streams and deposited where the stream slows down
delta: a low triangular area of alluvial deposits where a river divides before entering a larger body of water

Other hyponyms of alluvium include placer.

alluvium (noun)	delta (noun)
clay or silt or gravel carried by rushing streams and deposited where the stream slows down	the 4th letter of the Greek alphabet
	a low triangular area of alluvial deposits where a river divides before entering a larger body of water
	an object shaped like an equilateral triangle