Which is smaller?
 

Which is smaller in size, Gnome or KDE?

KDE has the fun familiar feeling that I like but I am looking more for a small desktop environment.

Both are heavy size. They are not comparable either, both can vary too much depending on how do you configure them and what features do you exactly use.

Your best bet is to try both of the, configure them to work as you like, and see how much ram is being occupied on each case if you really care about it. But in my opinion, if ram usage or disk space really matters better use a standalone wm.

Both are quite large but KDE is larger and more CPU and memory intensive than Gnome.
For a lightweight desktop you can try XFCE or LXDE. Both use fewer resources and run better on older hardware.

The lightest linux distro would be a custom kernel with text based tools on a floppy. There are many distros that are like that.

However the original poster didn't ask about that. He just wanted to know about the lightness of desktop environments.