The Ethernet switch serves the same function as a hub, in that it is the center of a star wired network, but it handles traffic much differently. A switch has much more available bandwidth than a hub. On a switch, EACH PORT has its own exclusive allocation of bandwidth. A 12 port 100mbps switch, for example, has 1.2gbps of network bandwidth capacity (12 ports x 100mbps).
The Ethernet switch makes intelligent decisions about where a packet entering a port is supposed to go. As it known, Ethernet is a collision-based protocol. Switches essentially eliminate collisions on an Ethernet network, because the switch is aware of the MAC address of every device on the network. The switch is also capable of analyzing packets as they enter a port, and forwarding them based on the destination MAC address. Hubs are dumb-- they cant make these routing decisions.