sole definitions of avoid and evade are completely irrelevant, "tax avoidance" and "tax evasions" are well understood syntagms, former meaning utilizing any legal means in order to reduce the amount of taxes paid. simply put, tax avoidance is good accounting. tax evasion is illegal and is an action in which you're directly breaking a law.

what tech companies were doing in europe was utilizing every possible loophole in order to reduce the amount of taxes paid. of course, that angered sovereign nations which (rightly) felt cheated and they acted by applying pressures to ireland and others. some (france) even fined some of the companies, those fines were most likely in a grey area, but tech firms knew very well what they were doing, understood the motivations behind those fines and generally concluded that it's a bad idea angering a nation in whose market you're operating. realpolitik.