I have had good luck with the release drivers, as the developer drivers don’t seem to work as well with OpenCL as they do for CUDA (they probably havn’t touched the OpenCL drivers in a long while, sigh).
As for the difference between the developer and release drivers:
“The developer driver is released with the Toolkit and is intended to have wide support for all CUDA capable devices. On the other hand the drivers on the main driver page are released as appropriate; the main drivers have full support for CUDA, but each one may support a subset of devices.”