ones smoother casting, ones tougher, (xl / xt). I have been using Suffix for the last 10-12 months after years of Stren use. I like it, and it seems to me to be a little smoother on the spinning use. But I respool spinning reels very often anyway. Where I have noticed it the most is on my crank bait rods, and it has held up and cast very well. For pitching the heavier line is smooth, but I would stick to the Siege for heavy cover only.