The different degree sizes are simply the angular distance from the elevator attach point.

120° means the pitch and aileron attach points (bottom half of swash) are 120° from the elevator attach point. This gives you three attach points (360° / 3 = 120°).
140° swash is just a modified version of the 120° swash. As Druss stated, the 140° swash has the pitch and aileron attach points 140° away from the elevator attach point. This gives slightly more symmetrical elevator and pitch function.

The other common type is 90° in which the attach points are 90° from each other. You could have either 2 or 4 attach points in this case.
90° with 2 attach points (aileron and elevator) is common with fixed pitch helis and helis that generated collective pitch changes via some other mechanism besides the up/down movement of the swash.

The 90° with 4 attach points are usually two aileron and two elevator attach points and the pitch mechanism lifts all four points at the same time. This is commonly called a standard or non-CCPM swash config.