Please try to search a little harder about what you're questioning before posting the thread. A quick Google search would have shown you than the Traxxas Rustler XL5 is an electric 1:10th not a nitro.
Moved to Misc. Electric.
Also, a little more search would show you that they are indeed one of Traxxas' top selling chassis/models and have proven to be great RCs.
From the first picture you posted (
This One), the grey chassis on top of the image is the Rustler XL5. The black one on the bottom is just a Rustler built prior to the XL5 ESC/chassis. Due to the crappy quality of the second image, I cannot tell if it is an XL5 Rustler or just a Rustler. I see a slight bit of yellow which leads me to believe it is an XL5 Rustler because the XL5 ESC has some yellow while the XL1 ESC (used in the previous version of the Rustler) is black and blue (or black and black, depending on year).