it means less cable (LC)... so your paying for or not for the cable, the mic is the same... whether you want their cable, or another cable, or the cable you already may have is up to you
Yes, they are literally the same mic. The box is the same, the mic is the same, everything is the same except that one is supposed to come with a cable.
I realize that this is a very old thread, but I'm finding that the SM57 doesn't seem to come with a cable anymore (as the poster from 3 years ago stated). For $99 I can get the mic and sometimes it's labeled "LC" and sometimes it's not, but never comes with a cable.
All of the Shure mics can be ordered with a cable but for the money there are better cables out there, plus very often retailers make up a bit or margin on the cable since Shure mics are so deeply discounted.