International mostly means something (a company, language, or organization) involving more than a single country. The term international as a word means involvement of, interaction between or encompassing more than one nation, or generally beyond national boundaries. For example, international law, which is applied by more than one country and usually everywhere on Earth, and international language which is a language spoken by residents of more than one country.
Tourism is travel for pleasure or business; also the theory and practice of touring, the business of attracting, accommodating, and entertaining tourists, and the business of operating tours. Tourism may be international, or within the traveller's country. The World Tourism Organization defines tourism more generally, in terms which go "beyond the common perception of tourism as being limited to holiday activity only", as people "traveling to and staying in places outside their usual environment for not more than one consecutive year for leisure, business and other purposes".
Slow travel now rivals the fly-to-Barcelona-for-lunch culture. Advocates savour the journey, travelling by train or boat or bicycle, or even on foot, rather than crammed into an airplane. They take time to plug into the local culture instead of racing through a list of tourist traps.
Carl Honore in: The perfect time to slow down, The Guardian, 23 July 2008
I sat on a toilet watching the water run thinking what an odd thing tourism is. You fly off to a strange land, eagerly abandoning all the comforts of home and then expend vast quantities of time and money in a largely futile effort to recapture the comforts you wouldn’t have lost if you hadn’t left home in the first place.
Bill Bryson in: Neither Here Nor There, Doubleday Canada, 25 September 2012, p. 204