The first trailer introduces us to the "fluff" scoring system. It was coins with Mario, rings with Sonic, and marshmallows for LittleBigPlanet. The more fluff the more items you get to make game levels.
The race to beat the clock at the end was also cool.
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The second trailer shows LittleBigPlanet in edit mode. The ease of creation will make the game levels almost infinite.
[Source: Sony PS3 Modding - Homebrew, Upgrades, Mods, and Hacks]