There are many differences between the two types of wire. Spiral-O-Wire was developed to fit into the same hole pattern as plastic comb binding. It is a twin loop wire, but the spacing between the loops is farther apart than double loop wire. Also, there aren't as many sizes and color choices with Spiral-O-Wire. Double loop wire has two different pitches 2:1 and 3:1 depending upon the size of wire you need for the book. Double loop wire has less spacing between the twin loops and is more stable than Spiral-O-Wire. If you can't tell which wire to choose, please give us a call and we can help you with your decision.