This is an employment structure similar to freelancing but not limited to a particular project in the way that freelancing usually is. A person in fractional employment splits their time into blocks which they can then offer to different employers for whom they do different and often specialised jobs. The blocks of time can add up to full employment if they wish or to any variation of part employment depending on their needs. They have variety in their jobs and if one drops out they still have the others to sustain them.
By comparison a part-time job gives fixed hours for fixed income which might seem more desirable in terms of security.
Fractional employment can be seen by some as the answer to the current demand for flexible employment.