Basically, there's a green terror from Ecaudor (A. rivulatus), the one you commonly see and which can have either gold (to orange or reddish) fin edges or white fin edges and a green terror from Peru (A. stalsbergi) which is much more rare in the hobby. Rivulatus (the common one) has the dark spots in the scale centers, stalsbergi (the rare one) have the light scale centers and dark scale edges, not difficult to distinguish once you recognize this difference. Opinions differ on whether the white edge and gold edged rivulatus are the same fish, are simply different color morph populations of the same fish, or should be classified as different fish. Officially, they're classified as the same species for now (rivulatus).
Essentially, "green terror" is a nickname that applies to either species of Andinoacara (former Aeuquidens). Some people insist there is a "true" green terror and a "false" green terror, but this is something of a contrived hobbyist argument without much scientific relevance. The real question among experts over the years was which was the true
rivulatus, some older books and articles saying what is now stalsbergi was the true rivulatus, which turned out to be opposite current classification.
That's the short and simple version. For a more detailed explanation and history
here's an article by biologist and cichlid writer Wayne Leibel. Amusingly (or confusingly), Wayne's article refers to a 1982 German article, The Green Terror That Isn't, that talks about a fish the author
thought was rivulatus, but which we now know to be stalsbergi, that was different from what at the time was considered the 'true' green terror. In other words, in the German article, the "false" green terror was what some people now insist is the "true" green terror.
You can see why it gets confusing. Again, to sum up, there's the common fish, A. rivulatus from Ecaudor, which can have either white or gold edged fins and has the dark spots in the center of its scales. There's the rarer fish, A. stalsbergi, from Peru, with white fin edges, light scale centers and dark scale edges. And either one can be and has been called green terror.