split-pea soup vs soup

split-pea soup and soup both are nouns.

Word	Noun	Adjective	Verb	Adverb
split-pea soup	Yes	No	No	No
soup	Yes	No	Yes	No

As nouns, soup is a hypernym of split-pea soup; that is, soup is a word with a broader meaning than split-pea soup:

split-pea soup: made of stock and split peas with onions carrots and celery
soup: liquid food especially of meat or fish or vegetable stock often containing pieces of solid food

split-pea soup (noun)	soup (noun)
made of stock and split peas with onions carrots and celery	liquid food especially of meat or fish or vegetable stock often containing pieces of solid food
	an unfortunate situation
	any composition having a consistency suggestive of soup

split-pea soup (verb)	soup (verb)
	dope (a racehorse)