More often than not, we hear the term data transfer and bandwidth being interchangeably used in the web hosting world. This, however, is a fallacy as they are two completely different terms representing different measurements. Data transfer is the total amount of bytes of data that a server transfers to a given websites during a particular period of time. Majority of the
web server services provider tend to measure the amount of data transferred over a 30 day period. Bandwidth is the amount of data that can be transferred at one time. In other words it is the maximum amount of data that is transferable in a given period of time.
We can distinguish between the two with the help of a simple example. You can consider bandwidth to a bridge where the wider the bridge, the larger the number of vehicles that can pass through it. Data transfer then would be the number of vehicles that are allowed to travel over the bridge during any given time period.
Website loading time of your website is directly proportional to your bandwidth i.e. higher the
bandwidth faster is the loading time of your website. The less data transfer you have, the more often you will find your website failing to load.