You've linked competing hardware encoding APIs which are not x264/x265.

x264/x265 are software encoding libraries for H264/H.265 video formats and don't really use hardware acceleration beyond SIMD instructions on CPUs. x264 is known for its great output quality while still being fast on x86 CPUs.

I think kasabali was talking about x264 (https://www.videolan.org/developers/x264.html) and x265 (http://x265.org/) specifically rather than the H.264 and H.265 video formats in general.

x264 and x265 refer to the specific set of software programs of the same name, right? Most chips nowadays can hardware accel H.264 and H.265, but they don't use x264/x265 (or do they? Not sure...). I think the confusion is that the terms x264 and H.264 are not interchangeable