which gcc am I using?

I am attempting to compile a package on my Mac laptop and my Mac Mini desktop. It compiles successfully on the laptop, but not the mini (gives the following error: gcc: error: unrecognized command line option '-Xarch_x86_64'). Both machines are running OS X Yosemite (10.10.2). On both machines, when I type

which gcc

I get:

gcc: aliased to nocorrect gcc

(I don't know what this means) When I type

echo $PATH

I get:

/usr/local/bin:/usr/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin:/opt/X11/bin

This makes me think that if a gcc is found in /usr/local/bin, that's the one that will be my gcc. When I type

ls -l /usr/local/bin/gcc

I get:

/usr/local/bin/gcc -> /usr/local/bin/gcc-4.8

on both machines. However, when I type

gcc --version

on the Mini I get:

gcc (Homebrew gcc48 4.8.4) 4.8.4

Copyright (C) 2013 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.

and on the laptop I get:

Configured with: --prefix=/Applications/http://ift.tt/1d5DwEL --with-gxx-include-dir=/usr/include/c++/4.2.1

Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn)

Target: x86_64-apple-darwin14.1.0

Thread model: posix

Which is the version installed by XCode. (This is what I get on both machines from /usr/bin/gcc --version)

How is the laptop using gcc 4.2 when the first gcc in my path is a symlink to gcc 4.8, and how do I make the mini do the same?