actress vs leading lady

actress and leading lady both are nouns.

Word	Noun	Adjective	Verb	Adverb
actress	Yes	No	No	No
leading lady	Yes	No	No	No

As nouns, leading lady is a hyponym of actress; that is, leading lady is a word with a more specific, narrower meaning than actress:

Other hyponyms of actress include starlet, tragedienne.

actress (noun)	leading lady (noun)
a female actor	actress who plays the leading female role