An information processor includes a display unit configured to display page content of each of a first page and a second page expressed in a page description language, a difference detection unit configured to detect a difference between an object included in the first page and an object included in the second page by analyzing an object structure in page description data of each of the first page and the second page and by comparing the first page and the second page which are each in a state of an object of the page description data, and a display control unit configured to control the display unit to display information on the difference detected by the difference detection unit.