grande dame vs madam

grande dame and madam both are nouns.

Word	Noun	Adjective	Verb	Adverb
grande dame	Yes	No	No	No
madam	Yes	No	No	No

As nouns, madam is a hypernym of grande dame; that is, madam is a word with a broader meaning than grande dame:

grande dame: a middle-aged or elderly woman who is stylish and highly respected
madam: a woman of refinement

Other hypernyms of grande dame include dame, gentlewoman, lady, ma'am.

grande dame (noun)	madam (noun)
a middle-aged or elderly woman who is stylish and highly respected	a woman of refinement
	a woman who runs a house of prostitution