grande dame vs ma'am

grande dame and ma'am both are nouns.

Word	Noun	Adjective	Verb	Adverb
grande dame	Yes	No	No	No
ma'am	Yes	No	No	No

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

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

Other hypernyms of grande dame include dame, gentlewoman, lady, madam.

grande dame (noun)	ma'am (noun)
a middle-aged or elderly woman who is stylish and highly respected	a woman of refinement