My experience has been they both kill the weeds. Round Up seems to act quicker and you usually seed results in a couple of days. The other sometimes takes a week. I first noticed in a Lowes when looking at quart size that the Round Up they had was something like 18% so it took a lot more to equal the same concentration as I believe it was Total Kill that was 41%. The stuff I bought at Tractor Supply said it had a surfactant in it which based on the way it foamed, I suspect it was basicly dish washing soap. After the 1st tank mix, I started putting in most of the water before adding the weed killer to avoid so much waiting on the foam to go down. Oh well, used the time lubing the FEL.