Subdomains and addon domains both let you run more than one hostname, but they solve different problems. Understanding the difference helps keep projects organised.
What Is a Subdomain?
A subdomain sits under an existing domain, such as shop.example.co.uk or billing.example.co.uk. It is useful for separate areas of the same brand or service.
What Is an Addon Domain?
An addon domain is a separate domain hosted in the same account, such as anotherbusiness.co.uk. It has its own site files and DNS records.
Use Subdomains For
- Staging sites.
- Client portals.
- Billing systems.
- Apps connected to the same brand.
Use Separate Domains For
Use a separate domain when the brand, audience, email, or ownership is different. It keeps the identity clearer and reduces future migration headaches.
Whichever you choose, keep document roots separate so one site does not accidentally expose another site's files.
Choose by Ownership and Purpose
Use a subdomain when the service clearly belongs beneath the main domain, such as portal.example.co.uk or docs.example.co.uk. Use an addon domain when it represents a separate website with its own name and audience. Search engines and visitors can treat either as distinct content, so the technical label does not replace a clear information structure.
Plan DNS and Certificates
Each hostname needs the correct DNS record and HTTPS certificate. A wildcard certificate may cover first-level subdomains but not unrelated addon domains. Decide whether the hostname points to the same hosting account, another server or a third-party platform before creating it in the control panel.
Separate Security and Maintenance
Give separate sites their own databases, users, backups and deployment notes. If one application is compromised, shared account permissions can still expose neighbours even when document roots differ. For unrelated clients or owners, separate hosting accounts provide a cleaner boundary than addon domains in one account.
