Differences between "parked domains" and "add-on domains"
What is a Parked Domain?
A parked domain is one which simply points to an existing domain. So let's say you have domain1.com.au which you want to park on your maindomain.com.au (your main domain in your web hosting account). You would simply use the Parked Domains section in cPanel to add domain1.com.au as a parked domain.
Once added, anyone going to domain1.com.au with their browser will see your main domain's web page in their browser but with your parked domain's URL.
You will need to have registered the parked domain and pointed the NS records to the same settings as your main domain.
What is an Add-on Domain?
Add On domains offer you the capability to have more than one web site on your hosting package. You will of-course already have a main domain on your account (the one that you set up your hosting account with in the first place).
To have an add on domain, you will first need to register another domain name (or point an existing domain you have already registered to our servers). Then you will need to use the Add-on Domain feature in your web hosting control panel (cPanel).
When you add an add-on domain, your control panel will ask you for a user name and password. It uses the username to create a directory within your public_html directory which will house all files relating to that domain. The password allows for independent ftp access to that domain's directory and files.
An add on domain uses the space and bandwidth available to your main domain and each add on domain does not have its own control panel. You can access stats and add-on domain configuration using your existing control panel for your main domain.