Subdomains are "branches of a domain", for example, testing.yourdomain.com.au, login.yourdomain.com.au, staff.yourdomain.com.au. They can be used to host web pages that may or may not be connected to your main website. You are also able to set the A record for a subdomain to another server if you wish. They share the CPU/RAM/Disk Space and other resources of your cPanel account.
Addon domains are completely different domains that are added to a cPanel account. Their main purpose is to host multiple websites on a single cPanel account, and can also be used for email. Although they are connected to the same cPanel account as the main domain, to anyone who visits the website or sends an email for an addon domain the main/addon domains are completely transparent from and don't look linked to each other in any way. They share the CPU/RAM/Disk Space of your cPanel account. You can create individual subdomains for addon domains just as you can a normal domain.
Parked (Aliase) domains
These domains are like Addon domains however they can't be used to make a new website. By default when you go to a domain that's parked it will go to the website of the main cPanel account. However, this can be changed by using the redirects option in cPanel. Click here for a guide on using the cPanel Redirect tool.
** Our Business Hosting plan allow up to 20 Addon domains. For Reseller, VPS and Blaze plans you can set your own Addon domain limits from WHM > Edit a Package
What is the difference between subdomains, addon domains and parked (aliase) domains
To make it easier to get in touch with us, from the 24th of March 2016 all support tickets will need to be submitted from your Crucial Control Panel.