noble vs viscount

noble and viscount both are nouns.

Word	Noun	Adjective	Verb	Adverb
noble	Yes	Yes	No	No
viscount	Yes	No	No	No

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

noble (noun)	viscount (noun)
a titled peer of the realm	a British peer who ranks below an earl and above a baron
	(in various countries) a son or younger brother or a count

noble (adjective)	viscount (adjective)
having or showing or indicative of high or elevated character
of or belonging to or constituting the hereditary aristocracy especially as derived from feudal times
impressive in size, manner, or appearance
inert especially toward oxygen