gastroenteritis vs intestinal flu

gastroenteritis and intestinal flu both are nouns.

Word	Noun	Adjective	Verb	Adverb
gastroenteritis	Yes	No	No	No
intestinal flu	Yes	No	No	No

As nouns, gastroenteritis and intestinal flu are synonyms defined as:

gastroenteritis and intestinal flu: inflammation of the stomach and intestines; can be caused by Salmonella enteritidis

Other synonyms of gastroenteritis include stomach flu.

gastroenteritis (noun)	intestinal flu (noun)
inflammation of the stomach and intestines; can be caused by Salmonella enteritidis	inflammation of the stomach and intestines; can be caused by Salmonella enteritidis