Hiking gives walking a different feel or flavor. Hiking generally also means walking for longer distances than most of our other walking, but this is not absolutely true. Many hikes are for only part of day. A very short hike could be less than a mile on a nature trail by a campground. On the other hand a hike can be a very long walk.
Some people hike for days, weeks, or even months at a time.
A few people have even hiked for several years at a time. Another nice thing about hiking it s free. You've probably heard the saying that the best things in life are free. I think this certainly applies to hiking. There may be some fees at trailheads for parking your car, and a few places may charge a small fee for a trail permit in areas that are heavily used.