Hi, you can check the city's port schedule to see where your cruise ship has its booking, for Sydney -
https://www.portauthoritynsw.com.au/cruise/sydney-cruise-schedule/
The OPT is the Sydney Overseas Passenger Terminal which is situated conveniently at Circular Quay, where there is plenty of accommodation, transport links including to the airport, as well as cafes, restaurants and sightseeing.
White Bay is used when the OPT is already fully booked and for ships that can fit under the harbour bridge. It's not quite as convenient a location for visitors as the OPT is, but not impossible as it's still just a taxi ride away.