The differences lie in their ability to help you carry weight. Backpacking Boots are designed for 50+ lb loads over extended days. They are stiffer and heavier. Hiking Boots are meant for carrying your light day pack and just wondering around the woods. Both of these titles are focused on mainstream backpacking. For those looking to lighten up, Backpacking boots are too heavy, and hiking boots are borderline too heavy. If you aren't carrying 50+ lbs, you don't need backpacking boots.

As a side note, I have a pair of heavy, all leather backpacking boots (Dunham Wafflestompers). They fit my feet perfectly, are very comfortable, and have amazing ankle support. I hurt my ankles pretty badly in high school and have always thought I needed the support. But, this site convinced me to at least try trailrunners. I found a pair of Merrel Chameleons on sale that fit, and decided to try them. I have been VERY surprised. Especially when I went on a day hike carrying 40 lbs (a child carrier with a 30 lb child plus extras, children are so heavy). I would walk up steep slopes of loose gravel and sand, or steep slopes with rocks, and my ankles never had a problem. Now, I only wear my Dunhams in the snow.