GI tract vs gastrointestinal tract

GI tract and gastrointestinal tract both are nouns.

Word	Noun	Adjective	Verb	Adverb
GI tract	Yes	No	No	No
gastrointestinal tract	Yes	No	No	No

As nouns, GI tract and gastrointestinal tract are synonyms defined as:

GI tract and gastrointestinal tract: tubular passage of mucous membrane and muscle extending about 8.3 meters from mouth to anus; functions in digestion and elimination

Other synonyms of GI tract include alimentary canal, alimentary tract, digestive tract, digestive tube.

GI tract (noun)	gastrointestinal tract (noun)
tubular passage of mucous membrane and muscle extending about 8.3 meters from mouth to anus; functions in digestion and elimination	tubular passage of mucous membrane and muscle extending about 8.3 meters from mouth to anus; functions in digestion and elimination