Collabora Office 5.0 pulls in features from upstream LibreOffice 5.0 as well as some backported features from LibreOffice 5.1. Collabora Office 5.0 features improvements to the Microsoft filters, UI enhancements, remote file open/save support, security fixes, and much more.
Collabora Office is backed by enterprise support from the company and other enhancements but unfortunately on a demo is free, as available via their product page. This also isn't to be confused with any of their online web-based office endeavors with LibreOffice Online.
You can read more about Collabora Office 5.0 via CollaboraOffice.com.