The Prince and the Pauper.
(Book)

This historical satire, played out in two very different socioeconomic worlds of 16th-century England, centers around the lives of two boys born in London on the same day: Edward, Prince of Wales and Tom Canty, a street beggar. During a chance encounter, the two realize they are identical and, as a lark, decide to exchange clothes and roles -- a situation that briefly, but drastically, alters the lives of both youngsters. The Prince, dressed in rags, wanders about the city's boisterous neighborhoods among the lower classes and endures a series of hardships; meanwhile, poor Tom, now living with the royals, is constantly filled with the dread of being discovered for who and what he really is.