cPanel offers three ways to add a domain, and choosing the wrong one causes confusion.
ADDON DOMAIN
A completely separate website on the same account, with its own folder, its own email and its own certificate. Requires its own registered domain.
Use it for: a second business, a client site, any genuinely different website.
SUBDOMAIN
A section of a domain you already have, such as blog.yourdomain.com or staging.yourdomain.com. Free, and needs no registration.
Use it for: staging copies, customer portals, documentation, separating a shop from a brochure site.
ALIAS (PARKED DOMAIN)
A second domain that shows the same website as an existing one. Both addresses load identical content.
Use it for: owning .com, .com.ng and .ng versions of your name, or protecting a common misspelling.
A NOTE ON ALIASES
Serving identical content on two addresses can split your search rankings. In most cases you should redirect the alias to the main domain instead of mirroring it. The Aliases tool has a Manage Redirection option for exactly this.
All three are created from cPanel > Domains. Run AutoSSL after adding any of them.
