In Act 2, Scene 2, Juliet is most definitely presented as the more sensible, practical, and rational character through several things she says.
Juliet's response upon first discovering Romeo in the garden is one thing that portrays her as the more sensible of the two. When Juliet realizes it is Romeo who is speaking to her in the garden, her first response is to be incredulous that he managed to enter the garden and to ask him how he got there and why, plus warn him of the danger he has put himself in, as we see in her lines:
How cam'st thou hither, tell me, and wherefore?
The orchard walls are high and hard to climb,
And the place death, considering who thou art,
If any of my kinsmen find thee here. (II.ii.66-69)
Not only that, she continues to warn him in her next few lines that he'll be killed if he is seen.
We further see her acting more sensibly of the two when, after he proclaims his true love for her, she tells him she feels that he should not now swear that he loves her. She feels that right now making proclamations of faithful love "[i]s too rash, too unadvis'd, too sudden" (124). Juliet is perfectly right to believe that they are behaving far too rashly.
Finally, we also see her behaving more sensibly when we see her insist that their relationship will not continue unless Romeo is bent on marriage, as we see when she states, "If that thy bent of love be honourable, / Thy purpose marriage, send me word to-morrow" (148-150). Juliet is dedicated to remaining a virtuous young woman and, therefore, will not permit Romeo to court her, regardless of her feelings for him, unless he wants to do the virtuous thing by marrying her.
Romeo begins to display signs of increasing maturity in this scene. His speeches are now in blank verse rather than the rhymed iambic pentameter evident in his earlier sonnets and couplets. Romeo is no longer the melancholy lover of Act I. Up to this point, Romeo has expressed his emotions in a traditional, colloquial style. His behavior has been notably antisocial — he preferred to submit to the misery of his own amorous failures.
Although Romeo has matured in the brief time since the beginning of the play, he remains somewhat immature when compared with Juliet — a pattern that recurs throughout their relationship. Although Juliet is only 13, she considers the world with striking maturity. As later acts reveal, her parents do not provide an emotionally rich and stable environment, possibly forcing Juliet to mature beyond her years.