I'm looking for a netbook, but i really don't know which is the difference between those technologies. Which is the best for outdoor use of a netbook?
TFT is a type of display technology ( http://en.wikipedia.org/wiki/Thin-film_transistor). It's pretty standard. I'm not sure you'll do better, unless you're looking at E-Ink type technology, which is fine for reading books outside but which isn't so great (just MHO) for many other computer tasks.
XWGA and WSVGA are resolution settings ( http://en.wikipedia.org/wiki/Display_resolution).
One word of warning: more is not always better ( http://superuser.com/questions/143891/linux-virtualized-screen-resolution). I'm also finding my 1920 x 1200 screen to be a real pain in the tail because all the text is too small, although 1920 x 1080 is the screensize for HD video.
Instead of trying to evaluate different technologies, I suggest looking for reviews of particular products. At the end of the day, it's all about the implementation.