Directory Sorting DOS verses Windows

When sorting a directory using the /on switch in a DOS Window the file order is different from sort on the the name in Windows Explorer. Any idea what is causeing this? I limit my file names to 8 charactors below is a directory name sample:
A2c—a-.tif
A2c–aa-.tif
A2c—b-.tif
A2c—b1.tif
A2c–bb-.tif
A2c—c-.tif
A2c–cc-.tif