greater peritoneal sac vs peritoneal cavity

greater peritoneal sac and peritoneal cavity both are nouns.

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

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

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

greater peritoneal sac (noun)	peritoneal cavity (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