Lancaster vs royal line

Lancaster and royal line both are nouns.

Word	Noun	Adjective	Verb	Adverb
Lancaster	Yes	No	No	No
royal line	Yes	No	No	No

As nouns, royal line is a hypernym of Lancaster; that is, royal line is a word with a broader meaning than Lancaster:

Lancaster: the English royal house that reigned from 1399 to 1461; its emblem was a red rose
royal line: royal persons collectively

Other hypernyms of Lancaster include dynasty, royal family, royal house, royalty.

Lancaster (noun)	royal line (noun)
the English royal house that reigned from 1399 to 1461; its emblem was a red rose	royal persons collectively
a city in northwestern England