What is the difference between and lady and a flower girl, according to Eliza? Do you agree with her? Explain your answer. (Act 5)

From the text:

You see, really and truly, apart from the things anyone can pick up (the dressing and the proper way of speaking, and so on), the difference between a lady and a flower girl is not how she behaves, but how she’s treated.

Yes, I'd have to agree with her. People respond in the same way they're treated. If you're treated like a lady (or a gentleman), you'll tend to act like one.