Whats the difference betwen a switch and a hub?

A hub is a dumb switch.

A hub receives packets and asks everyone plugged into it who is this person. Computer respond with I am that Person. Packet is sent. And repeat. So it causes a lot of extra traffic.

A switch. Makes a list of who is in which computer so each packet is oh this guy, toss to him. If it doesn't belong to him the computer reply with that's now me and it broadcast once, to find where he is.

Thats my quick answer.

Hubs are only good for Lan party, now a days if you cheap and don't want to pay extra for a switch.

Edit: If a hub could not handle it, it would explode into million pieces with smoke saying pwned. A hub is more inefficient if you have more than 2 computers on it. But this only effects it if you transfer alot of data back and forth causing collisions which is pretty much 2 computers send packets and the hub drops them because it can't do two at a time because it needs to do a broadcast to find the other computer. a switch will just take one send it to the next location and continue.

Kevin has the right basics.

Another explanation is a switch is a store and forward device, a hub is just an electrical signal repeater (in simple terms). Store and forward devices can take several packets to forward to several destinations at the same time. That is, 4 computers, A,B,C,D - A can talk to B and C can talk to D all at the same time, at full speeds. You cannot do that with a hub. When A talks, the hub sends it to all, B,C and D and waits for that reply.

A hub lags more because it cannot handle the traffic, switch handles the traffic better.