Er, if you're referring to the minecraft that you get from the store, you only download the game and nothing else. To play on classic, you either play using the online web client or download a third party application. :s
Minecraft has both singleplayer and multiplayer mode for either survival or creative gameplay. Creative is pretty similar to how classic works, except that you are given the ability to fly by double tapping the space key to get off the ground, and then using shift or space to go up or down. You're offered a larger variety of blocks to build with, and many of them aren't simple blocks. For instance, you have fences, doors, red stone circuity (if you want to make machines), flower pots, pistons, etc...
I haven't played on minecraft in a while so I'm not entirely sure how the ranks work out. I know that your builds are protected though as long as you're in a designated zone for your builds in the creative world, or if you're in your town area in survival.