What is subdomain, alias or parked domain, addon domain vs alias domain?

Subdomain is a domain that is formed from the highest level domain zone and an additional domain, separated by comma. For example support.goodhoster.net is a subdomain for a goodhoster.net, therefore goodhoster.net is a subdomain of a domain net. If you have a domain name, for example goodhoster.net, an add to it any domain ( support or 123best) we will have a subdomain 123best.goodhoster.net and so on.

Parked domain (or alias) is an additional domain name that is associated with your web-site as an additional site address. For example you have a domain that is connected to your site. Later you buy another domain and want your web-site to be available by both addresses. Then you simply add a second domain as a parked domain in control panel, so both domains will represent the same web-site.

Addon domain is an additional domain name with a sepparate web-site on your account. When you have one site, and you want to add a second one on your hosting plan, then you add a new domain as an additional in control panel, so the separate folder and a ftp account for the second web-site are created. In the shared hosting the amount of additional domain names shows how many web-sites you can have in one account.