Difference between HUB & SWITCH

Today they are almost the seem. many hub has the functions of switcher. and mny swither has functin of router.

See link:

Switch or Hub

A switch is a "smart" hub. It is able to divide a network into multiple segements, perform as a high speed selective bridge between segments, and support simultaneous connections of multiple pairs of computers which do not compete with other pairs of computers for network bandwidth.

This is accomplished by maintaining a table of each destination address and port. When the switch receives a packet, it reads the destination address from the header information in the packet, establishes a temporary conection between source and destination ports, sends the packets and terminates the connection.

The hub does none of this. As a result, collisions are possible as the packet is sent out to every connected computer or device on the hub.

The hub is fine if there is little traffic. The hub is cheaper than the switch.

I do agree with you. Here could be added informal rule: if number of needed to be routed nodes not exceed some a few (<10) so there can be applied a simple hub. If number of nodes is significant (48 for instance) there should be employed properly adjusted switch.