The VMware UEM product is one of the newest editions to the Horizon portfolio and was added when VMware acquired the Dutch company Immidio back in February 2015. Immidio was a software company that created products that were aimed at helping their consultants out in the field, with the core product being called Flex+.
UEM adds additional functionality over and above the standard persona management solution, providing a central management console, to deliver personalization of the end user's virtual desktop machine as well as the ability to dynamically configure policies. It works across several different environments, such as virtual desktop machines, physical PCs, as well as cloud-based Windows desktop environments or DaaS. It's all about managing Windows profiles regardless of where or how the operating system runs.