What are the major differences, advantages and disadvantages?
Cambridge is generally seen as being more difficult than NCEA in most subjects, but perhaps less demanding than the IB. Similarly, it will open up a wider range of opportunities (especially in the UK) than NCEA will. IB and CIE are recognised fairly similarly in places such as the US. Overall, I think a decision should come down to how much time you’re willing to put into your studies - IB will take up a lot of your time, whereas CIE is more demanding towards the end of the academic year, and NCEA is generally considered as less demanding overall.