peritoneal cavity vs greater peritoneal sac

peritoneal cavity and greater peritoneal sac both are nouns.

Word	Noun	Adjective	Verb	Adverb
peritoneal cavity	Yes	No	No	No
greater peritoneal sac	Yes	No	No	No

As nouns, peritoneal cavity and greater peritoneal sac are synonyms defined as:

peritoneal cavity and greater peritoneal sac: the interior of the peritoneum; a potential space between layers of the peritoneum

peritoneal cavity (noun)	greater peritoneal sac (noun)
the interior of the peritoneum; a potential space between layers of the peritoneum	the interior of the peritoneum; a potential space between layers of the peritoneum