gastrointestinal system vs digestive system

gastrointestinal system and digestive system both are nouns.

Word	Noun	Adjective	Verb	Adverb
gastrointestinal system	Yes	No	No	No
digestive system	Yes	No	No	No

As nouns, gastrointestinal system and digestive system are synonyms defined as:

gastrointestinal system and digestive system: the system that makes food absorbable into the body

Other synonyms of gastrointestinal system include systema alimentarium, systema digestorium.

gastrointestinal system (noun)	digestive system (noun)
the system that makes food absorbable into the body	the system that makes food absorbable into the body