Addon domains: Addon domain are fully functional websites but are managed from the main domain’s control panel. They share the resources of the main account and are a good way to host multiple domains in a single account.
Parked domain : These domains simply point (redirect) the visitor to the main domain. They do not have any content of their own and do not take any web space of your main account.
Sub-Domains : They are basically created to better organize a large site. So a big shopping site will have billing.shop.com, sales.shop.com, etc. They are simply folders created in the main site’s webspace.