The terms casual and part-time are often used interchangeably, but they mean different things — and the difference affects how you should write a listing and what workers expect.
Part-time employment means a fixed, agreed number of hours per week, below full-time. A part-time worker has a roster. They expect it to be consistent. They get leave entitlements. They're employees in the traditional sense, just working fewer hours.
Casual employment means you offer shifts as they come up, and the worker can accept or decline each one. There is no guaranteed minimum. In most jurisdictions, casuals get a loading on their hourly rate (often 15–25%) to compensate for the lack of guarantee and leave entitlements.
Why it matters for your listing. If you want someone for a recurring roster slot — the same nights every week — write 'part-time, X hours per week, consistent schedule'. Workers looking for stability will apply. Workers who want maximum flexibility may not.
If you want someone available when you call — event backup, shift cover, high-season extra — write 'casual, shifts offered as available'. This attracts students, people with other jobs, and workers who want to set their own pace.
The pay difference. If you're advertising casual work, include the casual rate. If you'd written '$18/hr' but the actual casual rate is $20.70 (at 15% loading), post $20.70. Workers who understand casual employment will read it correctly. Workers who don't will be pleasantly surprised.