Okay I will agree with this. But helical will never be offset. Helical will always be way more than an offset. Hence the differences in the names and meanings.Dale.......So, they are totally the same just to a less degree. Anytime you have a line that is not perfectly down the center of a cylinder it creates a helical/spiral. An "offset" is merely a small degree helical/spiral gained off of using a straight clamp. Look up the definition of helical.
Here is what Bohning think about it.. I just put it hereHelical.
356, they are not the same