delta vs geological formation

delta and geological formation both are nouns.

Word	Noun	Adjective	Verb	Adverb
delta	Yes	No	No	No
geological formation	Yes	No	No	No

As nouns, geological formation is a hypernym of delta; that is, geological formation is a word with a broader meaning than delta:

delta: a low triangular area of alluvial deposits where a river divides before entering a larger body of water
geological formation: (geology) the geological features of the earth

Other hypernyms of delta include alluvial deposit, alluvial sediment, alluvion, alluvium, formation.

delta (noun)	geological formation (noun)
the 4th letter of the Greek alphabet	(geology) the geological features of the earth
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