milk tooth vs primary tooth

milk tooth and primary tooth both are nouns.

Word	Noun	Adjective	Verb	Adverb
milk tooth	Yes	No	No	No
primary tooth	Yes	No	No	No

As nouns, milk tooth and primary tooth are synonyms defined as:

milk tooth and primary tooth: one of the first temporary teeth of a young mammal (one of 20 in children)

Other synonyms of milk tooth include baby tooth, deciduous tooth.

milk tooth (noun)	primary tooth (noun)
one of the first temporary teeth of a young mammal (one of 20 in children)	one of the first temporary teeth of a young mammal (one of 20 in children)