I see these debates often all over the place. Many times I read XFCE is just as light or something there about. This isn't the case and anyone who has ever ran LXDE and XFCE for more than 'testing' would figure out quite quickly, once you have been using it for a week or more, that while fast and very nice, it's not quite as snappy or light on resources as LXDE and I'm basing that off of personal experience in both environment for long periods of time and of course testing.

Now before any XFCE fans go totally crazy on me let me say this upfront. I started out on XFCE well over a decade ago, I actually chose it over gnome or kde of the time. I just simply liked it, I was also a fan of 'lightweight' back then. Speaking of 'back then' XFCE was quite a bit more like LXDE in those days, while nice, the features found today in it simply weren't there.

And that is really what it comes down too, features. All day long I'll agree that XFCE has an absolute ton of nice features, options, polish and manages to be more friendly for the new user. I've toyed with the idea of doing an XFCE version but honestly there are soo many distributions that feature it as their main desktop it's really unneeded and there are some really great ones too.

LXDE is about speed, it's what I like about it, while providing enough ease of use for the intermediate computer user to use, whether coming from another OS or not.

So what do you get in return being able to 'run' it. A faster system. Point blank and period. You also get to throw it on just about anything you have and it will run pretty darn well if not great. It's nice to have the same system on all your computers at times. Keeps things easy.

So without getting into this distro does this and this one does that, here are some general articles on the subject.

https://www.wikivs.com/wiki/Lubuntu_vs_Xubuntu
http://www.phoronix.com/scan.php?page=article&item=linux_desktop_vitals&num=1
https://l3net.wordpress.com/2013/04/09/a-memory-comparison-of-light-linux-desktops-part-2/
http://askubuntu.com/questions/517413/how-do-ubuntu-flavors-compare-regarding-resource-consumption-a...

While some would argue that system speed isn't simply about 'saving ram' and such, while true, there isn't much that software can do to change your hardware, outside of saving ram or perhaps some new driver. If your running any system that isn't close to brand new, you'll need every bit of actual ram that you can spare. Whats the cheapest way to make your computer faster? Ram, everyone knows that, so my rational is, I'll get some ram for free, by saving every bit of it I can, within reason, down to the very last megabyte. Perhaps an old school mindset, then again, the system is for 'old school' computers. ;)

To clear up the idea of 'saving ram'. Saving ram does much more than just dwindle down the numbers in your task manager. Saving ram coincides with also saving processes. The more ram you save the more likely you save the computer from performing extra processes in the background. So it's a two headed deal. You save ram which helps the applications you want to run, load faster and perform better. It also helps your processor have more power for the apps your working with, since the background processes have been slimmed down. Hope that helps clear the idea of 'saving ram'.