What is the difference between a Hex Rod and a Threaded Rod?
Hex rods have a hex shape on the end of the rod for attaching hole saws. A hex makes it easier to remove and replace a hole saw.
A threaded rod simply has threads on the end of the rod. The hole saw threads directly onto the rod.
Both the hex rods and the threaded rods have their benefits. The hex rod is designed to make it easy to attach and remove the hole saw from the drill rod. The only downside is that a shorter rod is needed for the 3/4" & 1" taps and a longer rod is needed for 1-1/2" & 2" taps.
Although a threaded rod is a little more challenging when it comes to removing the hole saw, one rod works for all taps.