basically:
A hub is a very simple device that connects computers & network
devices on a single physical lan. A network can be simply
extended/expanded by adding hubs or switches. A switch basically
performs the same role as a hub but is more efficient. (They can do a
little more than that but lets start simple.) Switches operate on the
data link layer unlike routers.
A router is a device that connects networks. It can be used to share
a single IP address. It is a much more sophisticated and complex
device that more actively directs & examines traffic. Routers make
decisions about traffic based on the network layer protocols (like IP,
IPX, etc.). Routers usually have firewall software & sometimes have
VPN software included. They allow traffic to travel among multiple
paths & can extend the speed, distance, & intelligence of lans.
google these terms as well as the "OSI Seven-Layer Model" for more
detail.
http://www.practicallynetworked.com/...idge_types.htm
http://www.asante.com/support/router...hardwared.html