1) Domain is defined as single unique domain address such as "www.domain.com" and "domain.com". Additional sub domains such as "support.domain.com" require additional licenses.
2) Portal is defined as a unique site within DotNetNuke Installation.
3) DNN Install is defined as collection of DNN Portals/Domains that are running off same DNN Database and Filesystem.
4) Enterprise is defined as your company site(s) and those of your customers that are directly managed by your organization.
5) 50% discount on major upgrades.

Please refer to our End User License Agreement for complete details