scarlatina vs scarlet fever

scarlatina and scarlet fever both are nouns.

Word	Noun	Adjective	Verb	Adverb
scarlatina	Yes	No	No	No
scarlet fever	Yes	No	No	No

As nouns, scarlatina and scarlet fever are synonyms defined as:

scarlatina and scarlet fever: an acute communicable disease (usually in children) characterized by fever and a red rash

scarlatina (noun)	scarlet fever (noun)
an acute communicable disease (usually in children) characterized by fever and a red rash	an acute communicable disease (usually in children) characterized by fever and a red rash