Juliet and her mother have a very formal relationship. Juliet especially treats her mother with formality. In Act 1, when Nurse summons Juliet for her mother, we see Juliet address her mother very formally as "Madam," saying, "Madam, I am here. / What is your will?" We also see Juliet answering her mother very politely when Juliet is asked if she thinks she can like Paris. She answers her mother in a way that shows her willingness to oblige her mother. She especially shows willingness to oblige when she refers to her mother's "consent" in the lines,
I'll look to like, if looking liking move;
But no more deep will I endart mine eye
Than your consent give strength to make it fly. (101-103)
In this passage Juliet is telling her mother that since she asked, Juliet will certainly look at Paris to see if she can like him, but she will not take the affair any further than looking because that is what her mother has given her consent to do.
In contrast, both Juliet and her mother are very informal with the Nurse. Lady Capulet reveals that the Nurse is privy to all of the family matters. We see this when Lady Capulet shoos the Nurse away so she can speak with Juliet privately, but then commands her back again, saying, "Nurse, come back again; / I have remember'd me, thou shalt hear our counsel" (10-11). We also see Juliet treat her Nurse informally when Nurse relays a story about Juliet's childhood and Juliet begs her to be quiet, saying, "And stint thou, too I pray thee, nurse, say I," which can basically be translated as Juliet begging her Nurse to stop.
The Nurse is also equally informal with both Juliet and her mother. In front of Lady Capulet, the Nurse takes the liberty of telling jokes, making puns, and telling a long rambling story about Juliet's childhood.