Ordinary rubber bands are sliced off the end of rubber tubing. The natural grain of the rubber runs across the width of the band. When the band is stretched the grain is opened. This speeds the drying and oxidation of the rubber, resulting in a shortened life... S N A P!
Bundlebands are specially made with the grain running with the length of the band. When stretched, the grain actually closes, preventing drying and oxidation resulting in much longer life!