Domo - Job Share
Job Share is different to a part time position - covered by the transition to retirement clause.
Job share - 2 people agree to work the roster of one full time employee. They can cover that position any way they like e.g. one works days, the other nights; one block on, one block off; 3 months on, 3 months off; etc. As long as the shift is covered.
Part time - company determines when you work subject to minimum hours. Shifts can be as short as 4 hours, split shifts, permanent nights, continually varying, whatever meets companies' requirements.
You can choose which you prefer. I know Job share is my preferred option and part time is the company's preferred option.