There are several differences between the two books. Nigel Holmes's contribution to Understanding The World is a double-page infographic, though he produced a poster for Information Graphics. Understanding The World is organised thematically (nature, science, economy, society, and culture), whereas Information Graphics was classified by format. While Information Graphics cited the sources in which its infographics first appeared, Understanding The World sometimes omits these citations.
Most significantly, Understanding The World's historical introduction is substantially shorter than that of Information Graphics. The few examples it cites are well chosen, though: Hartmann Schedel's Nuremberg Chronicle, Abraham Ortelius's Theatrum Orbis Terrarum (from which a world map is reproduced), and Denis Diderot's Encyclopedie.
As in Information Graphics, the historical examples remain the highlights of Understanding The World. These hand-drawn maps and diagrams were created hundreds of years before the computer-generated contemporary examples that dominate the book. (Fortunately, there are a few additional historical examples inserted into each chapter.) From the portfolio of recent infographics, one of the most interesting is Noah Smith's timeline Pulp Fiction In Chronological Order, a deconstruction of the film's convoluted narrative.