What are the differences between dual-field lenses and continuous zoom lenses?

Both are variable lenses with variable focal length and adjustable sharpness. But there is several fundamental differences:

A. Structurally, a continuous zoom lens has two sets of adjustable lenses, which are used to adjust the focus and sharpness respectively. The dual-field lens has only one set of adjustable lenses, which is used to switch focal length and adjusts the sharpness of the picture.

B. In General, continuous zoom lenses require two sets of motors to control. Dual-field lenses require only one set of motors to switch the focal length and adjust sharpness.

C. The focal length of continuous zoom lenses can be any value within the design range. Whereas the focal length of dual-field lenses can only be switched between the two fixed focal length.