Everytime I boot up Xubuntu, I get the question, XFCE session or Xubuntu session, what are the actual differences?
XFCE sessions offers a vanilla default XFCE layout (wallpaper, theme etc.) and Xubuntu session a personalized one. Menu are also slightly different. A suggestion : try both of them!
Xfce is available on other distros outside of Ubuntu. There are no major "apparent" differences aside from branding options. However using Xubuntu implies the ubuntu core files and packages are standard. You could run Xubuntu with different file managers etc but essentially then you are really just modifying XFCE.