Mail vs. mail what is the difference

What is this business about mail and Mail? [On a CentOS box] Why mail does not work but won't return an error either while Mail works fine with the exact same syntax? Mail is basically a link to mail, isn't it? Sorry, this was a mixup, apparently (for historical reasons?!) there is a mail and a Mail Nowadays it looks like they both point to the same thing, on my machine: sr-linux> ls -l which mail -rwxr-xr-x 1 root mail 66492 Jun 24 2001 /bin/mail sr-linux> ls -l which Mail lrwxrwxrwx 1 root root 14 Nov 19 2001 /usr/bin/Mail -> ../../bin/mail