The question is already asked and replied. William Shakespeare's As You Like It is a very witty comedy. Here, the characters of Orlando and Oliver are clearly distinguishable from each other.
Oliver is Orlando's elder brother. Both are the sons of late Sir Rowland de Bois. In the very beginning, we find out, in accordance with the rule of primogeniture in England, which instructs that all the property would be inherited by the eldest of the family, Orlando gets the possession of the belongings that his father leaves. Though, he was instructed to take proper care of Orlando, he, out of jealousy and loath, makes Orlando totally deprived. In fact, when the royal wrestler Charles is supposed to fight Orlando, Oliver leaps with joy thinking of the probable death of his brother. But, in Orlando, we find no such cruel feeling or motive. He is not even confident enough to stand on his own feet. He just flees away in fear of his brother.
Later in the play, when Oliver is attacked by a lioness in the forest of Arden, it is Orlando who rescues him. Orlando could have shown abhorrence or reacted vindictively by not saving Oliver, but he does not do so. Unlike Oliver, he proves to be a sensible brother and a good-natured human. And, at this point, his valour is also expressed.
Another notable point is that, Orlando's character develops gradually with the help of Ganymede, whereas Oliver's character faces a sudden change in the forest of Arden which is very miraculous.
The difference between the two brothers has clearly been depicted in the play, where Shakespeare's portrayal of Orlando is almost a mirror image of Oliver.