How does the OpenACC API relate to OpenMP API?

The creators of the OpenACC API are all members of the OpenMP Working Group on Accelerators, and are working to resolve differences between the draft OpenMP 4.0 directives for accelerators and the OpenACC 1.0 and draft 2.0 specifications. The OpenACC API is defined to be interoperable with OpenMP, and several implementations already support OpenACC accelerator regions within OpenMP parallel regions. The compilers from the OpenACC members exist today, and support accelerators from NVIDIA, AMD, and Intel.