flapper vs young lady

flapper and young lady both are nouns.

Word	Noun	Adjective	Verb	Adverb
flapper	Yes	No	No	No
young lady	Yes	No	No	No

As nouns, young lady is a hypernym of flapper; that is, young lady is a word with a broader meaning than flapper:

flapper: a young woman in the 1920s who flaunted her unconventional conduct and dress
young lady: a young female

Other hypernyms of flapper include fille, girl, miss, missy, young woman.

flapper (noun)	young lady (noun)
a young woman in the 1920s who flaunted her unconventional conduct and dress	a young female