carditis vs myocarditis

carditis and myocarditis both are nouns.

Word	Noun	Adjective	Verb	Adverb
carditis	Yes	No	No	No
myocarditis	Yes	No	No	No

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

carditis: inflammation of the heart
myocarditis: inflammation of the myocardium (the muscular tissue of the heart)

Other hyponyms of carditis include endocarditis, myocardial inflammation, pancarditis, pericarditis.

carditis (noun)	myocarditis (noun)
inflammation of the heart	inflammation of the myocardium (the muscular tissue of the heart)