bandwidth v throughput

my day today is full of conflict... the excitement never ends...

bandwidth is the theoretical potential a device has for transmitting based on some measured guideline.. for instance, fastethernet can have a a maximum data rate of 100mbs but you'll probably never see that happen...

throughput is the actual amount of data being transported at a given moment in time...

according to dictionary.com  

 Bandwidth:
A data transmission rate; the maximum amount of information (bits/second) that can be transmitted along a channel

Throughput:
The amount of data transferred in one direction over a link divided by the time taken to transfer it, usually expressed in bits or bytes per second. 

and mark this from

 http://learn-networking.com/network-design/a-guide-to-bandwidth-and-throughput

The Difference between Throughput and Bandwidth

Although bandwidth can tell us about how much information a network can move at a period of time, you’ll find that actual network speeds are much lower. We use the term throughput to refer to the actual bandwidth that is available to a network, as opposed to theoretical bandwidth.

Several different things may affect the actual bandwidth a device gets. The number of users accessing the network, the physical media, the network topology, hardware capability, and many other aspects can affect bandwidth.
To calculate data transfer speeds, we use the equation Time = Size / Theoretical Bandwidth.

Keep in mind that the above equation is actually what we use to find the “best download.” It assumes optimal network speeds and conditions since we use theoretical bandwidth. So to get a better idea on the typical download speed, we use a different equation: Time = Size / Actual Throughput.