GCC vs. Clang in Mountain Lion

gistfile1.txt

[bgeiger@Maximus][~/Desktop]$ which clang
/usr/bin/clang
[bgeiger@Maximus][~/Desktop]$ clang --version
Apple clang version 4.0 (tags/Apple/clang-421.0.57) (based on LLVM 3.1svn)
Target: x86_64-apple-darwin12.1.0
Thread model: posix
[bgeiger@Maximus][~/Desktop]$ which gcc
/usr/bin/gcc
[bgeiger@Maximus][~/Desktop]$ gcc --version
i686-apple-darwin11-llvm-gcc-4.2 (GCC) 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.11.00)
Copyright (C) 2007 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[bgeiger@Maximus][~/Desktop]$