In reply to IvanLi:
Hiking: Going for a long walk.
Trekking: Multi day long walks.
Mountaineering: Going up mountains.
Can you hike up a mountain? Yes.
Can you trek to a mountain? Yes.
Can you trek up a mountain? Yes.
Can you go for a hike on a mountain without mountaineering? Yes.
Can you go for a hike whilst also on a trek? Yes.
Does any of this really matter? No.