round shot vs projectile

round shot and projectile both are nouns.

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

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

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

Other hypernyms of round shot include missile.

round shot (noun)	projectile (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
	any vehicle self-propelled by a rocket engine

round shot (adjective)	projectile (adjective)
	impelling or impelled forward