Fedora LXDE Spin vs Lubuntu
Lubuntu and Fedora LXDE Spin are built on the two most popular Linux distributions (Ubuntu and Fedora, respectively). Both use LXDE, the "Lightweight X11 Desktop Environment".
 Default Web Browser
Fedora LXDE Spin comes with the Midori web browser. Lubuntu comes with the Chromium web browser. Both browsers work well on a computer with limited memory and processing power. Chromium is more widely-used, which means it may be easier to find support if it encounters problems, and to find extensions for it.
 Package Management
Lubuntu is compatible with .deb files, while Fedora LXDE Spin is compatible with .rpm files. Deb files are slightly more common. Lubuntu also makes it easy to install support for a variety of proprietary file formats (.wmv,.mp3,etc.) by installing the Ubuntu-Restricted-Extras package. Installing free software is very easy on either distribution and both have a wide variety of free software available for download (mainly through their repositories).