Diskspace is the size your website can be. Every single letter on your website has to be stored somewhere on your web host's server. Each letter is one byte, and a megabyte is roughly one million bytes. HTML pages are usually very small, but it is the extra images, scripts, and even databases that can take up large amounts of disk space.
Bandwidth/Transfer is the amount of data the server will allow your site to send in a month. Transfer is usually measured in gigabytes - billions of bytes.
To review your used and available disc space and bandwidth log in to your cPanel. In the left cloumn you can find this information. Here you can see exactly how much disk space, bandwidth, sql resources, email resources, and domain resources you have used so you are able to see when you need more resources allowing you to up-sell yourelf.
