Subdomains -
Subdomains are URLs for different sections of your website. They use your main domain name and a prefix. For example, if your domain is johndoe.com a sub-domain of your domain might be support.johndoe.com
The number of sub-domains vary according to plan purchased.

Addon Domains - Currently not available

Parked Domains - Parked Domains (Domain pointers) allow you to "point" or "park" additional domain names to your existing hosting account. This will allow users to also reach your website when entering the "parked" or "pointed" domain into their browsers.
The number of parked domains vary according to plan purchased.

Redirects - Redirects allow you to make a specific web page redirect to another page and display the contents of that page. This way you can make a page with a long URL accessible by a page which has a shorter and easier to remember URL.