Clarification regarding x264 build

[ioncube]

I needed an x264 build with audio support to skip further encoding steps. So I downloaded two of the following x264 builds but I don't know what is the difference b/w the two.

1. x264_32_tMod-8bit-all-ffmpeg.exe ~14mb
2. x264_32_tMod-8bit-all-libav.exe ~12mb

I can't differentiate them even after reading the attached readme files?

[jagabo]

One is built with libav, the other with ffmpeg.

[ioncube]

and what is libav & further isn't x264 a library of ffmpeg.