rubella vs epidemic roseola

rubella and epidemic roseola both are nouns.

Word	Noun	Adjective	Verb	Adverb
rubella	Yes	No	No	No
epidemic roseola	Yes	No	No	No

As nouns, rubella and epidemic roseola are synonyms defined as:

rubella and epidemic roseola: a contagious viral disease that is a milder form of measles lasting three or four days; can be damaging to a fetus during the first trimester

Other synonyms of rubella include German measles, three-day measles.

rubella (noun)	epidemic roseola (noun)
a contagious viral disease that is a milder form of measles lasting three or four days; can be damaging to a fetus during the first trimester	a contagious viral disease that is a milder form of measles lasting three or four days; can be damaging to a fetus during the first trimester