Being an equipment junkie I love that question. First because it means that people are beginning to understand that there is a difference and second because I get the chance to educate them about those differences, helping them to make a good decision about the poles they will purchase.
In a nutshell: Trekking or hiking poles are designed for hiking or walking on uneven ground. Their job is enhancing stability and balance on the trail. You might be carrying a back pack or simply on a day hike but if you are on a trail going up or down hills that features rocks and other obstacles you are trekking. A trekking pole looks more like a downhill ski pole and typically has 3 sections to adjust small enough to fit into a backpack and tall enough for your personal height. It is the “mountain bike” of the pole world.
Nordic Walking poles are all about fitness walking. Although stability and balance is definitely one of the many advantages of adding poles to your walk it is not their primary purpose. Nordic Walking poles are used to increase heart rate and calorie burn, engage more muscles, and add a strength component to your basic walk. They typically look more similar to a cross country ski pole altho there are some that come strapless. Nordic Walking poles are the “road bike” of poles.
Now can you use a trekking pole to Nordic Walk? The reason we have specially designed poles is so that we can match the equipment to the activity. If I really want to reap all the benefits of the poles I need the pole that is made specifically for Nordic Walking. And I will tell you to buy the best pole that you can afford to purchase. Purchasing equipment is an investment in health, not just a decision about what to have for lunch. Be sure to buy the pole that you will be excited about using 5 years from now. We want you to be Nordic Walking for miles and miles!