It's differences training rather than a type rating - you will still have a class rating - SEP
that is not correct here, every aircraft requires a type rating in NZ. It needs to be ticked off by an instructor and for a c182 it would require a minimum flight time of 30 minutes.
As for the differences between a more basic aircraft you should know things like what type of injection system the engine has, what hydraulic system, all the V speeds for the gear and how to lower them in an event of hydraulic failure, any 'do nots' for the gear. What will happen to the prop in event of CSU spring failure or hydraulic failure and how to operate it/what RPM to use etc. Other than that your type rating will be much the same as any other single engine piston plane