The main difference is the shielding. One will do a better job blocking out noise then the other im simple terms.
yeah parts express doesn't go into detail on them, but, the 100 series has a single layer foil shield. The 200 series are actually pretty nice and are balanced, directional shielded cables. You probably wont get any noise in either one, but if you get noise in the 100 series, you probably won't in the 200 series. They are both older products that aren't sold now. There are no 100 series monster cables anymore. I wouldn't get them if I was you. The ones in the picture at parts express don't even look shielded really......
