Subdomain
A subdomain is a second website with a unique content and no new domain name. Instead, you change the www to another name. Examples are forums.domain.com, help.domain.com, and others.
Addon Domain
An addon domain is a second website, with a unique content. This type of domain needs a new domain name.
Parked Domain
A parked domain is NOT a unique website. It is a masked alias to the primary domain name of your cPanel account. Parked domains are commonly used when:
1. You need a place to park a domain for which you do not have a website
2. You have more than one domain that should lead to your primary domain
3. You have misspellings in your registered domain name
