I had been running Ubuntu on the desktop for a couple years. For the last couple months I've been using both Xubuntu on my laptop and Linux Mint (Cinnamon) on my desktop. Both are great desktop distros. Here's a quick summary of the differences I've seen between the two.
Features: I like both distros Mint and Xubuntu and view them as roughly tied. Generally Mint has more features, though a few areas feel like they could use more polish. But this makes sense because Cinnamon a relatively new interface compared to XFCE, and it's not an official Canonical release. Xubuntu is a bit leaner (fewer bells and whistles), but it is a very polished, light weight and a reliable workhorse OS. Xubuntu is a bit like the Gnome2 desktop, possibly trimmed down. In some ways, Xubuntu feels like Linux from the old days. Some people might like this aspect of XFCE, though I can equally see how others might not. XFCE reminds me both of Gnome2 (which was nearly flawless IMO) and my Redhat Linux desktop 15 years ago. XCFE tends to take the more classic Unix approach of "one-tool-does-one-job."
Speed: I like that XFCE let me easily turn off all desktop effects, including the compositor. I don't see a way to disable compositor in Mint. So, I would expect Xubuntu would run a little faster on older hardware. Standards application load a hair faster in XFCE, such as Thunar file manager -- these applications are a bit more lean (fewer features). Though I was surprised that some applications such as Chromium browser actually seem to load a hair faster in Mint (maybe because gnome dependencies?). Overall though, on a normal computer, I don't notice much difference in speed between the two.
Menus/panels: The only issue I've run into with Mint is in using Citrix Receiver, the bottom menu bar in Cinnamon is always visible. So, if I'm connected to a remote Windows machine, the Cinnamon menu sits on top of the Windows menu. I haven't found a work around for this. I see a similar issue in Xubuntu, but I can just select "Always On Top" from the menu bar, to bring the Citrix window to the front. While XFCE *looks* slightly simpler, it seems to be remarkably configurable, and can do things that Unity can't even do (for example, move the menu bar to the bottom of the screen).
Repository integration: Xubuntu's software center is a bit sluggish to load, though I do like that I can install multiple applications from the listing. Mint's software center runs faster, though I have to click the details page before I can install any application (a little more tedious). I like the built-in ratings, but overall, both the GUI's are possibly harder to use than Synaptic Package Manager (or even the command line).
Upgrades: Xubuntu allows upgrades on a system (in-place), where Mint requires a full reinstall. Granted, upgrades aren't always 100% reliable, so it might be best to avoid full upgrades. But overall, the integration with Canonical's software repository feels a bit tighter in Xubuntu. I actually like that it prompts when updates are available. In Mint, I have to remember to manually check for both software and kernel updates.
Default File Manager: Mint uses nemo and Xubuntu uses thunar. Nemo includes a lot of conveniences out-of-the-box.
If I rename a file in the file browser, Mint functions exactly how I'd expect -- the file is renamed in place. Xubuntu (thunar) will pop up a new window that prompts for the filename. I thought this pop up was odd, though it allows selecting multiple files to do a bulk rename.
I like that Mint makes it easy to create bootable USB flash drives (just right click on an ISO file). I've never used these very much be
fore, though having this baked into the file manager is nice. It saves a lot of burnt cds and dvds when testing out software.
In Xubuntu, to get a similar convenience I had to install a usb package UNetbootin. Open thunar and go to Edit -> Configure Custom Actions, then add a custom command for *.iso files:
unetbootin method=diskimage isofile=%f
The Thunar custom actions are saved in your home directory in the file .config/Thunar/uca.xml. An alternate usb package is usb-creator-gtk (it looks nice, but only seems to work for Ubuntu iso's).
Similarly, Mint (with nemo) makes it a bit simpler to share folders over a network: right click on a folder and you have an option to share it. In Xubuntu (thunar) you'll have to install packages samba and system-config-samba to manage shares. Then tools are under the System settings.
There are not many default bookmarks (aka shortcuts) in thunar's sidepane, though it is easy to add them if needed: right click a folder -> Send To -> Side Pane (create shortcut).
So, initially I wasn't a fan of thunar, though the missing functionality does make sense. Thunar avoids duplication of system administration functionality, yet it does make it fairly simple to add custom functionality if needed. It is a valid question how much functionality/weight should be placed in the file manager if these operations are used infrequently.
Firefox: I was surprised there's a prominent bug in Firefox in Mint, given that Firefox runs fine in all other versions of Ubuntu, and a browser is such a critical application. For example: if I close multiple tabs, Firefox will prompt me if I want to save the multiple tabs -- every single time. I check the box to stop prompting me, but it never remembers the preference. The fix is simple (delete a config file), though it concerns me how this sort of bug is introduced and not patched, if the software is supposed to be 100% compatible with Ubuntu's repo's.
Codecs: In xubuntu, you have to install the package xubuntu-restricted-extras if you want all the proprietary codecs and fonts. In Mint the codecs are already included.
Window borders: The standard Greybird theme in Xubuntu has 1px window borders which makes it nearly impossible to grab and resize the window. There are a couple workarounds for this, though I wish there was an invisible region around the window border, like in Gnome. Window borders in Mint are easier to use for resizing. I had to tweak the theme in Xubuntu to use slightly thicker borders.
Default color schemes: Mint uses a green color scheme, which looks a little bit like whitish-green mint toothpaste to me. I spent some time trying to change this to something else, but I didn't see an easy way to fundamentally change the color theme mint. Most of the themes in the admin area seem to only change the menu launcher and window borders. I did install another color theme, though to me all the choices looked over-saturated. Eventually I just got used to the toothpaste colors in Mint. Though this might be like the brown colors in Ubuntu. Initially I thought Ubuntu was the ugliest distro I'd ever seen, though I got used to the brown and eventually missed the brown when they moved to pink and purple. :) Xubuntu's choice of colors -- blue, black, grey -- is probably a safer route. Overall it looks clean.
Default Icons: I like the default Mint icons, especially for the home folder. The Mint icons have a bit more variety, where the default Xubuntu icons are only one color. Xubuntu does include the clean "Humanity" icons from core Ubuntu (though probably should include a blue-themed version). I installed the package elementary-icon-theme from the repos.
Default backgrounds: As superficial as a background is, it's fairly important in getting a first impression of a distro. Initially, the first time I installed Mint, I thought it looked like a wash of confusing grey. But when I changed the background to something darker, it became much easier to visually process. So, I am not a fan of the light backgrounds when using a light grey window theme. To me, it's too hard to see where the window stops and the background begins. Also, I don't like backgrounds with too much complexity. Personally, I just prefer darker blurry backgrounds to help make the windows stand out. In this regard I wish Mint had some more options on the default backgrounds. Xubuntu's default background is good enough, I never changed it. In comparison, Fedora probably has the best collection of wallpaper's I've seen to date.
Mouse Scrolling: One unusual feature with XFCE is how it handles mouse scrolling. When you scroll with the mouse, focus is transferred to the window the mouse pointer is above. This is slightly different behavior than Mint/MS Windows, where focus only transfers to another window if you click it. This might make it confusing if you move the mouse scroll button over the desktop background ... XFCE will cycle through the desktops.
Linux Mint XFCE: I only briefly looked at running XFCE on Mint. Though, given that Xubuntu can be upgraded (usually LTS upgrades are painless) and Mint cannot be upgraded, I didn't see a whole lot of advantage of running XFCE on Mint vs plain old Xubuntu. Any missing packages I install in Xubuntu would take less time than re-installing the whole Mint OS.
