lady vs madam

lady and madam both are nouns.

Word	Noun	Adjective	Verb	Adverb
lady	Yes	No	No	No
madam	Yes	No	No	No

As nouns, lady and madam are synonyms defined as:

Other synonyms of lady include dame, gentlewoman, ma'am.

lady (noun)	madam (noun)
a woman of refinement	a woman of refinement
a polite name for any woman	a woman who runs a house of prostitution