fetoprotein vs antigen

fetoprotein and antigen both are nouns.

Word	Noun	Adjective	Verb	Adverb
fetoprotein	Yes	No	No	No
antigen	Yes	No	No	No

As nouns, antigen is a hypernym of fetoprotein; that is, antigen is a word with a broader meaning than fetoprotein:

fetoprotein: any of several antigens that occur naturally in the fetus and sometimes in adults with cancer
antigen: any substance (as a toxin or enzyme) that stimulates an immune response in the body (especially the production of antibodies)

fetoprotein (noun)	antigen (noun)
any of several antigens that occur naturally in the fetus and sometimes in adults with cancer	any substance (as a toxin or enzyme) that stimulates an immune response in the body (especially the production of antibodies)