choppiness vs rough water

choppiness and rough water both are nouns.

Word	Noun	Adjective	Verb	Adverb
choppiness	Yes	No	No	No
rough water	Yes	No	No	No

As nouns, choppiness and rough water are synonyms defined as:

choppiness and rough water: used of the sea during inclement or stormy weather

Other synonyms of choppiness include roughness.

choppiness (noun)	rough water (noun)
used of the sea during inclement or stormy weather	used of the sea during inclement or stormy weather