Mechanically, they're the same camera with different nameplates. That applies to both the xxxD and xxxxD lines (Rebel in North America, Kiss in Japan, and xxxD/xxxxD everywhere else).
There are some minor software differences, for example video-capable Rebels come with NTSC as the default output, whereas xxxD's come with PAL, but that can be changed in the menus. Likewise, Kiss models sold in Japan have Japanese and English as language options, while those sold outside of Japan have more language options.