gastric mill vs gizzard

gastric mill and gizzard both are nouns.

Word	Noun	Adjective	Verb	Adverb
gastric mill	Yes	No	No	No
gizzard	Yes	No	No	No

As nouns, gastric mill and gizzard are synonyms defined as:

gastric mill and gizzard: thick-walled muscular pouch below the crop in many birds and reptiles for grinding food

Other synonyms of gastric mill include ventriculus.

gastric mill (noun)	gizzard (noun)
thick-walled muscular pouch below the crop in many birds and reptiles for grinding food	thick-walled muscular pouch below the crop in many birds and reptiles for grinding food