With regular contrails, it's a continual, consistent thing whereby a thin trail disappears within 10 seconds and remains constant as the plane progresses across the sky. With chemtrails, sometimes you see them stop suddenly. If you look at some older posts, there are also pictures where you see them curve around and fly the opposite direction. Since when do you see commercial flights that do that?
I've actually seen both together. That would defy your explanation, because one fades out like normal, the other doesn't. Same sky, same humidity, but different behaviors.