ground swell vs heavy swell

ground swell and heavy swell both are nouns.

Word	Noun	Adjective	Verb	Adverb
ground swell	Yes	No	No	No
heavy swell	Yes	No	No	No

As nouns, ground swell and heavy swell are synonyms defined as:

ground swell (noun)	heavy swell (noun)
a broad and deep undulation of the ocean	a broad and deep undulation of the ocean
an obvious change of public opinion or political sentiment that occurs without leadership or overt expression