marchioness vs Lady

marchioness and Lady both are nouns.

Word	Noun	Adjective	Verb	Adverb
marchioness	Yes	No	No	No
Lady	Yes	No	No	No

As nouns, Lady is a hypernym of marchioness; that is, Lady is a word with a broader meaning than marchioness:

Other hypernyms of marchioness include noblewoman, peeress.

marchioness (noun)	Lady (noun)
a noblewoman ranking below a duchess and above a countess	a woman of the peerage in Britain
the wife or widow of a marquis