Just have a look around.
Go to the Team9000 Wiki if you like.
Here's the basics:
The Team9000 server is a 'Classic' Minecraft server.
'Classic' Minecraft is free. You cannot make tools, there are no enemies, there is no night. All you do is build.
Beta, or 'Survival', is a game you have to buy. It is not free.
In Beta, you can build tools, fight enemies, and there is a day and night cycle.
The only way to get a customized skin is to buy Beta.
WoM is a client that runs Minecraft. Thus, there is no difference between the server that appears from WoM and the server that appears from minecraft.net.
WoM lets you fly.
There.