Hi Chathu,
The tungsten piston is avaialbe for both the Artisan and Classic. The foot control Classic can later be updated to PalmControl.
The difference between the Classic and Artisan is the stroke collar. The stroke collar on the Classic provides the power of several sized hand pieces in one. It is similar to setting the back swing of a hammer hitting a punch.
It can be set at a short back swing or longer one. The PSI flow through the foot pedal or PalmControl controls the power and speed within a given stroke length setting. It is similar to gears in a car. Set it in first gear (short stroke) and you have good low end, delicate control. Or set it in fifth gear and you can cut much deeper than in first gear. It can still cut delicate lines in fifth gear but it is easier to cut delicate lines in first gear. Continuing this analogy of gears, the Artisan is fixed in 3rd gear.
Here are a couple of previous threads
http://www.engravingforum.com/showthread.php?t=10985
http://www.engravingforum.com/showthread.php?t=1375