Do the unis know the differences in difficulty of eg. AP vs IB vs CIE vs NCEA?
The Unis know AP, IB and CIE well, but NCEA not as much. But the course you take won’t give you a significant advantage or disadvantage.
For example, if you did AP, IB, CIE they’ll have a good sense of your academics from your grades. If you did NCEA, they’ll pay more attention to your ranking at your school, because it’s a indicator of how well you’re doing compared to your peers.