international relations is divided into several theory groups. the old standards are
realism,
idealism,
marxism, and a few others.
realism is an understanding based on states acting as rational units with a set state goal. these states interact according to each's power. some theorists like the idea of hegemonic power and some like a balance. these internal arguments are progressive developments based on a paradigm formed by assumptions.
idealism is a view of a global system with independent actors who interact based on power and economics and culture and stuffs.
marxism is kinda like realism except everything is based on economics and specifically the internal contradictions of capitalism that will lead to its failure.
each of these broad theory bases is an extreme standard which forms the entire basis for how theoreticians look at the world. they qualify as paradigms. so do deconstructivism, etc. however. the ideas as to when war will occur and other things are smaller theories that occur within each of the paradigms.
it's really only a word for "larger theory". however, people have gotten carried away with it in the quest for the holy grail that overturns all previous thought.. even in subjects where you're just not gonna get it. then you end up with a discourse that is something like a sieve with a million little gaps in it. i am hoping to fill in those gaps in my career.