The meaning of the terms walking and hiking differ depending on what continent you are on. In the USA, hiking often refers to a more strenuous form of walking further defined by the terrain, the ascent and the distance. In the United Kingdom, walking is synonymous with hiking, and as in the USA, the levels of difficulty are defined to give the participant an idea of what to expect. There isn't a hard fast rule for defining the different levels but there are general guidelines and all involve measuring the terrain, the ascent and the distance.
This explanation is to give you an understanding of what Great Circle Route means when we talk about our walking holidays. We hike in the USA and we walk in most of the rest of the world --- and it means the same! We also have strolling options which means the same in all parts of the world. Strolling is at a much slower pace and we usually cover less distance while spending more time visiting a garden or historic site.
No matter where you are, if you are hiking or walking, there is a sense of your surroundings -- forest, coast, mountain, meadow, village, city, river bank -- and always a sense of accomplishment!