throughput vs bandwidth?

Hi hasanarcas,
Bandwidth is the theoretical maximum amount of data per second that can be transmitted on a link/ channel. It is measured in a unit of bits per second.

Throughput is the actual amount of data that can be transmitted on the same link. Due to impeding factors such as latency, jitter, and protocol being used, this unit is always lower than bandwidth.

For more information, you can refer to

What is the difference between throughput and bandwidth?

Network Latency vs Bandwidth vs Throughput

Bandwidth is a measure of how much data over time a communication link can handle, its capacity. This is typically measured as kbps (kilobits per second), Mbps (megabits per second) or Gbps (gigabits per second). Think of lanes on a road, a mile of eight-lane freeway has more capacity for cars than a mile of two-lane road.

Throughput is the actual amount of data that is successfully sent/received over the communication link. Throughput is presented as kbps, Mbps or Gbps, and can differ from bandwidth due to a range of technical issues, including latency, packet loss, jitter and more.

The below image illustrate the difference between Network Bandwidth and throughput 

Useful data (ctual amount of data) is Throughput while Bandwidth is actual allocated one. 

Simple Way.

I have 10mbps bandwidth allocated in DSL Connection but currently using only 3 mbps speed (throughput) right now