It's mainly an issue of context, and which word sounds most appropriate to you. Mainly, I would say "travel" is the most commonly used term, and is usually a verb. Voyage is used less frequently, and some people may ask you to repeat yourself, but the words hold the same general meaning. Voyage is generally used as a noun, while travel is used as a verb. "I want to travel this year." versus "That was an amazing voyage/trip!" A trip (again, depending on context) is the noun word for 'travel' So if I were to say "Are you going to travel this year?" One could respond "I already took a trip to Spain!" Now, a tour is generally a showing of a place. For example, "during my travels, I took a tour of several museums in France." Touring is synonymous with site-seeing. It's a trip, whose purpose is to educate you about where you are.

'Travel' is usually used as a verb and means a) to go on a trip or journey or to go to a place, especially one that is far away. 'His job requires him to travel frequently.' b) to go through or over a place during a trip or journey. 'They travelled around Europe.' c) To move from one place to another. 'He travels to work by train.' As a noun 'Travel' means the act or activity of travelling 'She doesn't enjoy foreign travel.' As a plural noun 'Travels' means trips or journeys to distant places 'We extended our travels for another week.' 'Voyage' is a long journey to a distant or unknown place over water or through outer space. 'The Titanic sank on her maiden voyage.' 'Trip' is a journey to a place that can be short or long for holidays, for work, for a particular purpose. 'A trip around the world.' 'She is away on a business trip.' 'He made a trip to the dentist.' 'Tour' is either a) a journey through different parts of a country or region or b) an activity in which you go through a place (a building or city) in order to see and learn about the different parts of it. 'They went on a tour of Italy.' 'We went on a guided tour of the museum.'

Definitions of journey on the Web travel: undertake a journey or trip travel: travel upon or across; "travel the oceans" the act of traveling from one place to another Definitions of voyage on the Web: ocean trip: an act of traveling by water travel on water propelled by wind or by other means; "The QE2 will sail to Southampton tomorrow" a journey to some distant place wordnetweb.princeton.edu/perl/webwn Definitions of trip on the Web: a journey for some purpose (usually including the return); "he took a trip to the shopping center". travel: make a trip for pleasure Definitions of tour on the Web: a journey or route all the way around a particular place or area; "they took an extended tour of Europe"; "we took a quick circuit of the park ... go: a time for working (after which you will be relieved by someone else); "it's my go"; "a spell of work" make a tour of a certain place; "We toured the Provence this summer" enlistment: a period of time spent in military service . Definitions of travel on the Web: change location; move, travel, or proceed, also metaphorically; "How fast does your new car go?"; "We travelled from Rome to Naples by bus"; "The policemen went from door to door looking for the suspect"; "The soldiers moved towards the city in an attempt to take it before night fell"; "news ... undertake a journey or trip make a trip for pleasure travel upon or across; "travel the oceans" the act of going from one place to another; "he enjoyed selling but he hated the travel" undergo transportation as in a vehicle; "We travelled North on Route. 508"