In Romeo and Juliet, when Juliet is left alone with her mother and then the Nurse, how do their responses differ?
I am going to assume, since you do not specify, that you are referring to Act III, scene v, just after Lord Capulet has exploded because Juliet refuses to marry Paris. He basically tells her to marry Paris or he'll kick her out to "Beg! Starve! Die in the streets!"
When he exits, the first person that Juliet appeals to is her mother, but she finds little comfort here. Lady Capulet says:
Talk not to me, for I'll not speak a word.
Do as thou wilt, for I have done with thee.
So, she basically washes her hands of the situation, even though it might mean her daughter turned out into the streets with nowhere to go and no way to support herself. She either doesn't care what happens, or is not willing to cross her husband in support of Juliet. Either way, she has no kind words for her daughter.
The Nurse, gives Juliet the advice to marry Paris. She tries to pretty up the suggestion by talking about how much better a catch Paris is than Romeo. She also thinks Juliet will be better off. She says:
. . .Beshrew my very heart,
I think you are happy in this second match,
For it excels your first; or, if it did not,
Your first is dead, or 'twere as good he were
As living here and you no use of him.
Speakest thou from thy heart?
And from my soul too, else beshrew them both.
And so it appears she does speak from her heart. Though Juliet does not follow the Nurse's advice, it seems to be spoken from deep love and care. She certainly, unlike Lady Capulet, takes the time to do her best to counsel and comfort Juliet, behaving more like a mother to Juliet than her own mother does.