mumps vs epidemic parotitis

mumps and epidemic parotitis both are nouns.

Word	Noun	Adjective	Verb	Adverb
mumps	Yes	No	No	No
epidemic parotitis	Yes	No	No	No

As nouns, mumps and epidemic parotitis are synonyms defined as:

mumps and epidemic parotitis: an acute contagious viral disease characterized by fever and by swelling of the parotid glands

mumps (noun)	epidemic parotitis (noun)
an acute contagious viral disease characterized by fever and by swelling of the parotid glands	an acute contagious viral disease characterized by fever and by swelling of the parotid glands