The terms seem to be used interchangeably on many websites and travel books. It becomes even more confusing when some companies sell their boots as 'trekking boots' and then proceed to state that they can be used on long hikes. And when is a walk a trek and when is it a hike? It becomes even more confusing when the word trekking is used to refer to the ascent of a mountain, like Island Peak or Mera Peak in Nepal, both over 6000m and both requiring the use of technical climbing gear. How can they be called 'trekking peaks?'
The term 'hiking' is often used to refer to day walks in natural surroundings, on clearly marked paths. It is intended for leisure, recreation and the purpose of exercise. A small day pack is used to carry water, light weight fleece and snacks. In places such as Canada and New Zealand, the term is often used interchangeably with rambling , hill walking or tramping .
'Trekking', by contrast is considered to be more strenuous, covers greater distances across varying terrains, and requires camping over night and carrying heavy bags with food, sleeping bags and gear. The term is actually derived from the Afrikaans work, trek , which comes from the Dutch word, trecken , referring to a lengthy and arduous journey over vast distances and often, uncharted ground. It is often associated with the migration of people across land from one area to another.
Does this mean then that if a day hike is difficult, over rough ground and through thick forest with no paths, that it is a trek? In Australia, they would call this bushwhacking , and in other places they call it stamping . When you visit the Mountain Gorilla in Rwanda or Uganda, it is a one day hike, but through strict forest, over very uneven and difficult terrain. No wonder there is so much confusion.
But let us not end the confusion there. Anyone who has tried to take out travel insurance to cover their 'trekking' or 'hiking' trip, will have discovered that these activities are often listed as 'hazardous pursuits'. In fact, some insurance companies even lump terms like hiking and mountaineering together as through they can be used interchangeably or are harmonious The there are other companies who classify any hikes over an altitude of 2000m as mountaineering. Sorry Scotland, but it means that your peak peak, Ben Nevis (1352m), is not a mountain after all but simply a trekking peak?
Perhaps the best way to look at it is that a trek is generally completed over several days made up hiking, hill walking, tramping and bushwhacking.
At the end of the day, does it really matter? It is all about semantics and interpretation. The most important thing is that you enjoy it.