
With your tools you can build stuff, or transform it, copy it, or destroy it, or alter the landscape. You have a whole wheel of tools that do different things to the environment. I played the storyish mode where areas were already populated and built upon, but there is a free play mode where you can do anything like in Creative mode in Minecraft.
I think Lego Worlds is a bit more complicated than Minecraft. The Lego Worlds tools let you do more complicated things like copy objects. Minecrat is like one button push easy. In Lego Worlds you have to bring up a menu wheel and choose a tool, then figure out how it works exactly.
At one point, I found a plane on a land and started flying around. Then I realized red dots on the ground represented hidden chests that had lego plans in them. So I hunted them down. You end up with such a huge library of objects and parts though, it gets kind of overwelming.