Qwerty is the most common used keyboard layout, created in 1873. The name comes from reading the first six keys from top letter row of the keyboard.
Dvorak was created in 1930 and patented in 1936 by Dr. August Dvorak. It proponents claim this layout uses less finger motion, reduces errors and increases typing rate compared to Qwerty. 31 characters are different from Qwerty.
Colemak layout is designed to be a practical alternative to the Qwerty and Dvorak keyboard layouts, offering a more incremental change for users already accustomed to the standard layout.
Workman layout reduced lateral movement of the fingers and wrists, more balanced left and right hand usage. 21 characters are different from Qwerty.