Contractors are not classed as an employee. They will bring their own tools and equipment to work. A contractor gets to decide how to do the job by the deadline. So a contractor could work from wherever if possible and whatever hours might suit them best.1
A casual employee shows up when needed. They may not have to accept any offer of work.1 They are still entitled to paid leave.
A pay-as-you-go basis at the minimum rate of 8% of their gross earnings can be made if the work is irregular that's its impractical to provide them four weeks' annual holidays.2 The employee must agree to this in their employment agreement and the 8% gross earnings must be shown as an identifiable component of the employee pay.3
1.https://www.business.govt.nz/hiring-and-managing/deciding-to-hire/hiring-the-right-staff-types/
3.https://www.employment.govt.nz/leave-and-holidays/annual-holidays/fixed-term-changing-patterns/