AT first glance Bandwidth and throughput may appear to be same, like both having same measurement unit of bps, however both the terms are quite dissimilar with differences in table below –
Bandwidth actually gives the maximum amount of data that can be transmitted through a link or channel. Bandwidth does not consider latency and protocols type while considering the traffic traversing the link.
Throughput is defined as rate of successful information delivery over a communication link. That is the actual amount of data that gets transmitted back and forth from computer, through the Internet to the web server in a single unit of time. Several factors like delay, physical media and hardware capabilities can effect this reduction in the bandwidth. Protocols type and latency of link play a pivotal role in deciding throughput which is unlike in case of bandwidth.
A simple example of cars traversing a bridge would explain the difference in a better way.
1 car is taken equivalent to 1 bit of traffic
3 cars (3 bits) can simultaneously cross the bridge in half a second. This makes total of 6 cars (2 * 3 cars) that can cross the bridge in 1 second. Theoretically calculating, bandwidth of the bridge will be 6 bits per second (6 cars per second)
However the real conditions may differ. There are pits and speed breakers on the bridge which may incur delay and allow only 3 cars to take 1 second to cross the bridge .Now, considering the real conditions and delay caused by the road the throughput of traffic will be 3 bits per second (3 cars per second)
Bandwidth of traffic transmitted over the bridge = 6 bps
Throughput of traffic transmitted over the bridge = 3 bps
Both the terms may be defined as below –
Bandwidth == Maximum of the transmission media (Theoretically).
Throughput == Time taken to transmit given size of data (Real World)