round shot vs missile

round shot and missile both are nouns.

Word	Noun	Adjective	Verb	Adverb
round shot	Yes	No	No	No
missile	Yes	No	No	No

As nouns, missile is a hypernym of round shot; that is, missile is a word with a broader meaning than round shot:

round shot: a solid projectile that in former times was fired from a cannon
missile: a weapon that is forcibly thrown or projected at a targets but is not self-propelled

Other hypernyms of round shot include projectile.

round shot (noun)	missile (noun)
a solid projectile that in former times was fired from a cannon	a weapon that is forcibly thrown or projected at a targets but is not self-propelled
	a rocket carrying a warhead of conventional or nuclear explosives; may be ballistic or directed by remote control