I intend to use Linux Mint on a RAM/1GB laptop. I'm used with Xfce and LXDE and I see that both Linux Mint 14 Nadia and Linux Mint Debian have Xfce versions.Is there a reason to prefer one to the other - from this point of view? 
Is there a difference in resource use/requirements between Ubuntu and Debian versions of Linux Mint (under the same DE)?
ubuntu;debian;linux mint;xfce;resources
You may see some slight differences in resource usage from one distro to another when using the same desktop configured in the same way, but it should not be significant.In other words, as Ulrich said, no there is not a reason to prefer one to the other from this point of view!