A subdomain is a secondary website with its own content and uses the same domain as the main website. The subdomain name looks like private.domain.com and help.domain.com.
You can use cPanel to create subdomains and the function is free in all 2MHost web hosting packages.
An alias domain is not a separate website. It is just a masked forwarder to the main website of your hosting account; Aliases are commonly used when you need domain.net shows the same content or website of domain.com. We use 2mhosting.com as an alias of 2mhost.com!
In other words, domain alias is used when you want 2 domains to show the same website.
You can use cPanel to create aliases, and the function is free in all 2MHost web hosting packages.
An addon domain is a cPanel function that lets you host multiple websites in a single hosting account each with its own content and email. When we mention how many websites you can host in a single hosting account, we mean how many addon domains you are allowed to create in each hosting account + the main website.
You can use cPanel to create addon domains, addon domain's function is enabled in Personal-x2 packages and above.
We always recommend using separate hosting accounts for each website, for 3 reasons: