About a week ago Linux Mint 17 rc XFCE was released. Like MATE and Cinnamon, XFCE will be based off the 14.04 LTS and supported until 2019.
Update Manager is the big differentiator in this release. The big changes were a new "type" category was added and security updates can now bypass levels. The types differentiate between traditional updates, security updates, backports and romeo updates. As far as security updates the new setting determines if they should be viewed or selected. The default is set to view but not selected which means if you have your system at Level 3 and below, you will see the security updates (Level 5) but they will not be selected for install.
In the video I highlight the Update Manager too. In many ways in Ubuntu based distros this is what differentiates it as Linux Mint. I think it is more than Linux Mint simply tweaking the Ubuntu update manager, but is a clear differentiation in values, in particular, the relationship between an distro, its developers, and the users. Linux Mint at the end of the day trusts its users, and its Update Manager is a reflection of that. In this release it has added types, and gives more detailed information about security updates. It does this so you, the end user, can make the best decision for your system.
A question to ponder is since the central difference between Ubuntu and Linux Mint XFCE is the Update Manager, what does being based on the 14.04 LTS mean. For MATE and Cinnamon it is clear that staying on the LTS until 2016 means more development on the non-Ubuntu parts of those distros. Will the same apply to XFCE, should we expect more differentiation between Linux Mint and Ubuntu when the next LTS comes around.