There is only one ipad Minecraft and it can't be modified (unless you're a serious computer hacker type). I think this other kid has either spent more time developing his world or he is playing with others via wifi or he is playing survivor mode which your DS finds more exciting or he has used a seed. Google Minecraft PE seeds and you can get some codes that when you type in will generate a new world that is "enhanced".
Globetrotter- The PC version is definitely the most robust version for the enthusiast, but the ipad version is considered a good mobile version.