Currently AMD is at version 1.2 with their drivers and will eventually move to version 2.0 in the future. Compared to Nvidia's CUDA OpenCL is able to be used with Intel, AMD, ARM, and Nvidia hardware. For a developer OpenCL is better because it is useable by a larger consumer base than CUDA otherwise there is no real performance benefit from using OpenCL over CUDA or vise versa as of now.