Bandwidth vs Throughput
Bandwidth refers to how fast a device can send data over a single cable usually measured in bits per second. A great example of bandwidth is to imagine a Four-lane highway with traffic going in the same direction. The total width of the highway determines how many cars if side-by-side can fit on the road.
Throughput refers to how many bits are actually transferred between 2 computers or the average rate of successful message delivery over a communication channel. This data may be delivered over a physical or logical link or it may pass through a certain network node. Sticking with the cars on a highway reference, we'll say a car represents a packet of 64 KB. The round trip of that packet on the same highway (defined above) from the point of origin to a predefined destination and back represented in time (usually milliseconds) is the throughput.
An example of how to utilize bandwidth and throughput: Now that we have a basic understanding, we can use this information along with a throughput measuring tool to determine if any existing network speed is degrading. This could happen due to more traffic on the network than anticipated from the original design or perhaps a bottle neck, which if defined in our car example where the total width of the highway is not adequate enough to handle to amount of cars in a reasonable time at the high point that traffic is at its busiest.