Subdomain

* Let’s say your domain is mysite.com.
* You install a Message Board and put in in a directory called mysite.com/board/.
* You can turn the directory board into a sub-domain by adding it as a sub-domain from your Control Panel.
* Now you can access your Message board as either mysite.com/board OR board.mysite.com
* This costs you nothing and is free.

Parked Domain

* You have two domains mysite.com and my-other-site.com.
* mysite.com is the domain of your website and you want to add my-other-site.com.
* You want them both to go to the same place. In other words, when someone types either www.mysite.com or www.my-other-site.com they will go to the same page(s) on your website.
* In order to have additional parked domains you need to purchase them from registrar

Add-On Domains

* You have two domains mysite.com and my-other-site.com.
* You want the two domains to be totally separate/independent websites.
* In order to have additional add-on domains you need to purchase them