alimentary canal vs gastrointestinal tract

alimentary canal and gastrointestinal tract both are nouns.

Word	Noun	Adjective	Verb	Adverb
alimentary canal	Yes	No	No	No
gastrointestinal tract	Yes	No	No	No

As nouns, alimentary canal and gastrointestinal tract are synonyms defined as:

alimentary canal 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 alimentary canal include alimentary tract, digestive tract, digestive tube, GI tract.

alimentary canal (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