Exactly what I figured, wider, not longer. Some shoes (usually higher-end ones) have a width measurement (in letters) as well as a length (the usual number measurement) for this reason—you shouldn't need a longer shoe (larger number size) unless buying shoes that don't offer a variety of widths. In fact, getting a longer shoe for the extra width will result in a poor overall fit.
It's kinda like how some nicer brands offer a variety of size modifiers in addition to "small, medium, large" on their ready-to-wear shirts, like "slim", or Brooks Brothers' named fit-variants ("Regent", "Madison", et c)
