International
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.
International Relations
International Relations (IR) or International Affairs (IA) - commonly also referred to as International Studies (IS) or Global Studies (GS) - is the study of interconnectedness of politics, economics and law on a global level. Depending on the academic institution, it is either a field of political science, an interdisciplinary academic field similar to global studies, or an entirely independent academic discipline in which students take a variety of internationally focused courses in social science and humanities disciplines. In all cases, the field studies relationships between political entities (polities) such as sovereign states, inter-governmental organizations (IGOs), international non-governmental organizations (INGOs), other non-governmental organizations (NGOs), and multinational corporations (MNCs), and the wider world-systems produced by this interaction. International relations is an academic and a public policy field, and so can be positive and normative, because it analyses and formulates the foreign policy of a given state.
Tourism
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".
International Relations
According to the first image of international relations, the locus of the important causes of war is found in the nature and behavior of man. Wars result from selfishness, from misdirected aggressive impulses, from stupidity.
Kenneth Waltz, Man, the State, and War (1954).
Tourism
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
Tourism
I've taught the better class of tourist both to see and not to see; to lift their eyes above and beyond the inessentials, and thrill to our western Nature in her majesty.
Jonathan Raban in: Rebecca Brown, Mary Jane Knecht Looking Together: Writers on Art, University of Washington Press, 30 April 2009, p. 16