I wasn't assuming, just asking for confirmation. If you had a freewheel and had mistakenly called it a freehub you would be far from the first and certainly not the last. It's quite common for those new to wrenching to get these two mixed up. And without knowing how long you've been wrenching bikes it's often safe to ask.

Most threads on bolts and our axles are rolled to crush form the threads instead of being cut. That's why the thread crests are typically higher than the surface of the bare shaft. It may be that for whatever reason they rolled one pass further along and then the second finish pass was shorter. Without seeing your particular example that's just a guess. But it may explain why the flattened threads look smoothly ground down on that area.