There is no difference in how you play MySims
for the Wii or how you play MySims
for the PC. You are charged with bringing a town back from the brink of its own demise. You have the ability to use something called essence. Essence is the purity of objects you interact with. Manipulating essence is how you and you alone can save your town. Using essence can control and affect everything from the building design, to the plants that grow, or the people that move in. You build the buildings and design their layouts.
All of the same character customization exists. But, there is exclusive content with new locations, essences, and characters. You can also box up your objects that you make in-game. You can then email objects and files to one another. A player just needs to drop it into their corresponding game folder and the object appears in their game. Still, do not let the childish facade fool you. There is a lot more to this game. The game is now even more of a sandbox than the others. All of the new features open up an entirely new way to see this game. The main difference is now you can have other players actually join you in your little sandbox. You can have your friends join you in the world you create.
If you have your friend's "code," you can join in on the fun in their custom-made world. You can chat directly and interact with the world you create. Given the experience that EA had with The Sims: Online, I was surprised that they would "go there." It is a kid's game and you can only get codes directly from the friends you know, but someone somewhere will be trying to pervert this. Just guessing, though.