rubella vs German measles

rubella and German measles both are nouns.

Word	Noun	Adjective	Verb	Adverb
rubella	Yes	No	No	No
German measles	Yes	No	No	No

As nouns, rubella and German measles are synonyms defined as:

rubella and German measles: 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 epidemic roseola, three-day measles.

rubella (noun)	German measles (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