Ubuntu Multimedia :: Any Difference Between FAAC And LibFAAC?

Is there a difference between faac and libfaac? I have an iPod Shuffle.
One of these:-
It plays m4a tracks created using faac encoder.
Like this:-
Code:
ffmpeg -i foo.flac -f wav - | faac -o test1.m4a -b 152 -

But it won't play tracks created using libfaac.
Like this:-
Code:
ffmpeg -i foo.flac -acodec libfaac -ab 152k test2.m4a
I've compared the MediaInfo for the two files.

They look very similar, faac does a more thorough job of tagging. Does ffmpeg do something to the file when it's converting or muxing with libfaac to make it unplayable by the Shuffle?

I've uploaded the two files.
test1.m4a is created using faac
test2.m4a is created using libfaac
They are here:- [URL]. What's the difference?

Using Ubuntu Karmic 9.10
and
FAAC 1.26.1
and
FFmpeg version git-N-28456-g1c31b26