Here is a good place to start for an explanation of transparency anti-aliasing and adaptive anti-aliasing: Transparency & Adaptive AA Explained. The article is a few years old, but all of the information remains relevant.
I have one last question, does triple buffering improves performance if Vsync is off while gaming ?
Heh, I hate to answer your question with another link, but honestly, others have answers that are far clearer than my own: How VSync works, and why people loathe it.