Very little, each having elements of all three. In conventional UK parlance, the term ‘tour’ is most frequently used in connection with a hut tour in the European Alps and the term ‘trek’ in connection with something similar in the Greater Ranges, which may use bunkhouses, hotels or tents, and which is the sort of activity promoted by adventure holiday companies. The term ‘expedition’ is more usually encountered in connection with serious mountaineering in the Greater Ranges. The distinction between treks, tours and expeditions, in the insurance context, is explained in the AWS Leaflet Further Note : mountain rescue insurance is exactly what it says it is. It ‘reimburses the cost’ of mountain rescue, it does not ‘provide’ mountain rescue, and it cannot pay for what does not exist. So if you are operating in a very remote part of the world which lacks any mountain rescue facilities, your party might need to be self-sufficient for getting off the mountain.