I am a newcomer to the field of study of IR who's interested in understanding jargon such as "organization," "institution" and "regime". Are they interchangeably used or do they each have a unique region of understanding?
These are all pretty common terms in both political science and international relations. These below are uncited*, but you can check them against what your IR text book has. Any introductory course should cover these ideas.
Of course, if you are asking because of a class, you should always ask your instructor. Their definitions will be what you are graded on.
"Organization" is basically the common usage of the word. States are organizations, but so are organizations composed of states (such as the United Nations) as well as private organizations (such as private military contractors and humanitarian organizations).
Institutions are formal structures which shape how politics happens. Typical examples of institutions are constitutions, legal systems, legislatures, political parties, etc.
A regime is the kind of structure a government has. For example, we could refer to the United States as having a democratic regime. Sometimes news sources refer to a leader as having a regime (I recently heard a news article about the "Assad regime"), but under normal circumstances this isn't really a regime, just a leader.
* In the interest of providing a Good Subjective answer, these definitions are based on my background in political science. Although my specialty isn't in international relations, I think they are common enough terms that I can take a stab at them.
Definition of regime:
- a mode or system of rule or government: a dictatorial regime.
- a ruling or prevailing system.
- a government in power.
- the period during which a particular government or ruling system is in power.
From the French régime which comes from the Latin regimen, meaning government or governor.
In the third definition, some examples of regimes would be a monarch, a political coalition, or an elected executive (e.g. a president). The regime might be associated with an individual or more commonly with a group which the individual leads. It might even be a group where successive individuals take the lead.
A regime may be an organization but does not have to be. And most organizations are not regimes. So I wouldn't find those terms interchangeable.
Definition of institution:
- an organization, establishment, foundation, society, or the like, devoted to the promotion of a particular cause or program, especially one of a public, educational, or charitable character: This college is the best institution of its kind.
- any established law, custom, etc.
- any familiar, long-established person, thing, or practice; fixture.
The first definition has the most overlap. That kind of institution is an organization. But not all organizations are institutions. And institution has other meanings where it is not an organization. So not interchangeable.
Most regimes are not institutions. The definition suggests more permanence, where regimes are often temporary. We might talk about the Obama regime or the Bush regime. And of course regime has other meanings that aren't related to institutions.
These are three terms that overlap meaning. We could probably find historical examples of institutional organizations that acted as regimes. That is, something can be all three simultaneously. But you can't always substitute one for another in a sentence. Sometimes that will make sense and sometimes not.
Perhaps: The Roman Catholic regime controls Vatican City. The Roman Catholic church is an organization, an institution, and the governing body of Vatican City. But we might also talk of each individual Pope as being associated with a regime as well, part of the historical one but individual in application.