difference between non-builtin 'test' and '['

Question

I am aware that bash builtin test and [ commands are exactly the same, but what about /usr/bin/test and /usr/bin/[? I guess those two are not exactly the same as then one would be just a symlink pointing to another?

$ ls -l /usr/bin/test
-rwxr-xr-x 1 root root 30244 May  7  2012 /usr/bin/test
$ md5sum /usr/bin/test
681cefd6a38466fbc4898fd561b11905  /usr/bin/test
$ 
$ ls -l /usr/bin/[
-rwxr-xr-x 1 root root 34344 May  7  2012 /usr/bin/[
$ md5sum /usr/bin/[
f801cd22976ddd4f52c0de96fe1af633  /usr/bin/[
$