The difference is $200, exactly the value of the travel credit you get. Plat is widely seen as a better card for the advantages conferred, especially the Oneworld alliance wide status with Cathay Pacific Gold card, unlimited Priority Pass and SPG Gold status.

I would only recommend Aeroplat to those who fly almost exclusively AC in Canaa for MLL access, otherwise flying out of the hubs and internationally the Plat benefits are much better. Huge spenders may find they earn more Aeroplan on the Aeroplat card, however that is only if AP is not included as a bonus transfer partner for Amex (it has always been included twice per year until this year when it disappeared).