Microsoft Endpoint Manager is the name for all of Microsoft’s endpoint management solutions, and includes System Center Configuration Manager and Microsoft Intune. The benefit of Microsoft Endpoint Manager is that it makes it easier for organisations to concurrently manage Windows 10 devices with both Configuration Manager and Microsoft Intune, a configuration called co-management. Bringing everything up to date, the July 2020 Product Terms updates the name of System Center Configuration Manager to Microsoft Endpoint Configuration Manager.
In terms of co-management licensing, organisations don’t have to buy both Configuration Manager and Intune licences: if they are licensed for Configuration Manager then they are automatically licensed for Intune for co-managing Windows PCs, and if they are licensed for Intune, then they are also automatically licensed for Configuration Manager for co-managing Windows PCs. There are some management scenarios which aren’t covered with the co-management rights and this article has some useful instances of when you would also need a full Intune licence when you have a Configuration Manager licence, for example: https://bit.ly/2WIZieT.
There’s a name change but there aren’t changes to the licensing of Configuration Manager. As a recap, there’s a current branch and long-term servicing branch (LTSB) for Configuration Manager, with the current branch providing an active servicing model as you would expect. Customers who have active Software Assurance or a subscription to EMS E3 (for example) may use this branch. Configuration Manager must always be purchased with Software Assurance through a Volume Licensing agreement and the LTSB is intended for customers who have perpetual licence rights to Configuration Manager but have let the SA expire. This is a useful article if you want to learn more about branches and licensing: https://bit.ly/3hpw0JX.
And finally, there’s a Microsoft Endpoint Manager FAQ document which you may find useful here: https://bit.ly/32JtVog.