measles vs rubella

measles and rubella both are nouns.

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

As nouns, rubella is a hyponym of measles; that is, rubella is a word with a more specific, narrower meaning than measles:

measles: an acute and highly contagious viral disease marked by distinct red spots followed by a rash; occurs primarily in children
rubella: 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 hyponyms of measles include epidemic roseola, German measles, three-day measles.

measles (noun)	rubella (noun)
an acute and highly contagious viral disease marked by distinct red spots followed by a rash; occurs primarily in children	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