bearbo,
A hub and a switch are, although different, bascially the same thing. A hub is an older verion of a switch. They do the same job.
However, a router is a different thing. More advanced. From wiki:
A router acts as a junction between two or more networks to transfer data packets among them. A router is different from a switch. A switch connects devices to form a Local area network (LAN).
One easy illustration for the different functions of routers and switches is to think of switches as neighborhood streets, and the router as the intersections with the street signs. Each house on the street has an address within a range on the block. In the same way, a switch connects various devices each with their own IP address(es) on a LAN.
However, the switch knows nothing about IP addresses except its own management address. Routers connect networks together the way that on-ramps or major intersections connect streets to both highways and freeways, etc. The street signs at the intersection (routing table) show which way the packets need to flow.
As far as I know (only 99% sure) you can not plug a switch into your internet and 'split' your ethernet connection, so basically, this wouldnt work
Internet -> Switch -> Mac/Xbox
Where as:
Internet -> Mac (via USB) -> Switch (via Ethernet) -> Xbox/Second Mac/Whatever else
Would work. But thats only if you had a USB Modem. My setup is more advanced, because I have a PC downstairs and it goes kinda like this:
Internet (Cable) -> Router -From Router-> PC -Also from Router->Switch (Upstairs) -> then splits into Mac and Xbox360, etc.
Hope you understand this, if I'm wrong, please correct me. But to answer your question, Hub, switch... Basically the same. Router... Different.