There are similarities between Rosalind and Celia that are apparent in Act I, Scene III of As You Like It, but there are also some important differences that are significant. The most obvious similarities between Celia and Rosalind are that they are both princesses and daughters of dukes, who are actually brothers, Celia's father Duke Frederick being the younger. The second most obvious similarity is that they are both adept at word play and puns, making jests and persuasive arguments out twists on words and creatively used words:
Celia: No, thy words are too precious to be cast away upon curs; throw some of them at me; come, lame me with reasons.
Finally, a very important similarity is that they are both courageous. Rosalind and Celia both stand up to Duke Frederick and assert the truth of their position and the falseness of his.
The differences that are apparent in 3.1 are that Rosalind feels herself to be alone in her misfortunes whereas Celia believes that Rosalind and she are united as one since they have lived together so long as beloved cousins:
Celia:Rosalind lacks then the love
Which teacheth thee that thou and I am one...
And finally, it is Celia who can think more clearly under pressure and is more logical. It is Celia who decides they will go together. It is Celia who decides where they will go, to the forest of Arden where Rosalind's father is in exile. It is Celia who thinks of the first half of their plan for escaping. She suggests they both dress as "poor and mean" (lowly) maidens with dirt smudged faces. Rosalind finally contributes with the suggestion that because of her height, she could easily dress as a male and carry weapons, an act or courage in its own right considering the laws pertaining to men's and women's clothing.