People usually profile keys according to their rows. Row 1 is the one with space bar and the other modifiers. 2 is the shift row. 1 and 2 have the same height. Next is row 3, which has their own height. Row 4 also has its own height. Row 5(numbers) and 6(Fn) are the same height.
Shifts have their own size. Ctrl, Alt, Windows, and that thing next to the right Ctrl that i forgot the name have the same size. Tab and |\ usually have the same size. Enter is its own size, backspace also has its own size.