mesne lord vs Lord

mesne lord and Lord both are nouns.

Word	Noun	Adjective	Verb	Adverb
mesne lord	Yes	No	No	No
Lord	Yes	No	No	No

As nouns, Lord is a hypernym of mesne lord; that is, Lord is a word with a broader meaning than mesne lord:

mesne lord: a feudal lord who was lord to his own tenants on land held from a superior lord
Lord: a titled peer of the realm

Other hypernyms of mesne lord include noble, nobleman.

mesne lord (noun)	Lord (noun)
a feudal lord who was lord to his own tenants on land held from a superior lord	a titled peer of the realm
	terms referring to the Judeo-Christian God