Same type of cable, only the wires goto different pins on the connector at the end.
Normally a "straight" cable will be used to plug your network card (NIC) into a hub/network switch/router etc
A "Cross-over" cable is normally used when you want to plug 2 devices directly together (without using a hub/switch/router), i.e connecting 2 pcs together directly....or a xbox/xbox360 directly to the NIC card on your machine. A cross-over cable can not normally be used to connect a PC to a hub/switch/router, unless its on the uplink port (normally the last port)