Giovanni Virginio Schiaparelli vs stargazer

Giovanni Virginio Schiaparelli and stargazer both are nouns.

Word	Noun	Adjective	Verb	Adverb
Giovanni Virginio Schiaparelli	Yes	No	No	No
stargazer	Yes	No	No	No

Giovanni Virginio Schiaparelli (noun)	stargazer (noun)
Italian astronomer who first noted lines (which he called canals) on the surface of Mars (1835-1910)	heavy-bodied marine bottom-lurkers with eyes on flattened top of the head
	a physicist who studies astronomy
	someone indifferent to the busy world