Is throughput always less than bandwifth?

Throughput in megabits per second will always be equal to or less than the bandwidth in megabits per second (it can't be higher). Throughput decreases as latency increases. For instance if you send a file to your neighbor two houses down the latency should be very low (assuming you are on the same network). However, if you send it to another city the latency will be higher and while your bandwidth remains the same, your throughput will decrease due to the latency between the locations. Note that this can be improved by optimizing the TCP window size on your computers. There is a free TCP optimizer program available on the web if you search on that term.