I take FULL IB Diploma and I can tell you that 2-year program is time-wise more in depth than AP programs.
Not only that, in IB Diploma, you have to take Theory of Knowledge (TOK), produce an Extended Essay (EE) on the subject that you are interested in and also meet up with Creative, Action Service (CAS) credits. Not to mention that some people are taking 7 subjects or 4 Higher levels and 2 Standard Levels.
IB gives an all-around education and students see the interlinked-ness of the subjects through TOK, EE and CAS. I think it is more comprehensive than AP, which is 'class'-drive, not program-driven...
but that is just my opinion..
