1st one for Undocumented Keywords, which you will not find anywhere, not even in MSDN Documentation, which are not listed to intellesense menu in visual studio.
2nd one for Documented Keywords which are uncommon or just being introduced to C#. Documented keywords which are uncommon can be found over MSDN.I have also made a sample application where I have given some demonstration of each of the topics mentioned here in this article. If you want to test these, please download the sample application from here :
.png)
