The Prince and the Pauper.

Two boys – the prince Edward and the pauper Tom – are born on the same day. Years later, when young teenage Tom sneaks into the palace garden, he meets the prince. They change clothes with one another before the guards discover them and throw out the prince thinking he's the urchin. No one believes them when they try to tell the truth about which is which. Soon after, the old king dies and the prince will inherit the throne.