The two most popular stills are known as Pot Stills and Colum Stills (reflux still). The most popular still for making whiskey is a pot still. Whereas a Colum Still is most popularly used for making Vodka.
Whiskey is spelled either as whiskey or whisky. The reason for this has to do with a minor disagreement of what kinds of stills make the best kind of whiskey. Many Scottish distillers use Colum stills. Whereas Irish distillers tend to use pot stills. When the distilling industry really started to become industrialized, some Scotish distillers started using column stills. The Irish firmly believed that pot stills were superior. The Irish responded to this by adding an “e” to whisky. This was meant as a way to distinguish their whiskey from the Scots.
The main difference between Pot stills and Column stills is that alcohol made from pot stills tends to carry much more flavor from the grain. Whereas alcohol produced by Column stills typically have much less flavor. This is one reason the Column stills are exclusively used for making Vodka. Whereas pot stills are popularly used for making whiskey and Coniac.