They were always technically speaking compatible (Nougat and iOS10 have Unicode parity iirc, now Oreo pushes ahead with new Unicode points).
However, the blobs didn't always socially have the same meaning as iOS emojis. The push to the more circular emojis was to normalize them against iOS emojis, which for better or worse are the primary target of emoji use.
However, the blobs didn't always socially have the same meaning as iOS emojis. The push to the more circular emojis was to normalize them against iOS emojis, which for better or worse are the primary target of emoji use.