Blower is specifically referring to coolers that are designed to blow air through the GPU heats ink and then out the back of the case. In contrast, open air coolers use (typically more numerous and larger fans) to force air at the GPU heats ink but without much concern for where it goes after that, so the air ends up partially blown out the back of the case, and partially recirculate back into the rest of the case where the case fans are hopefully promoting enough exchange that ambient temps remain sufficiently low. The recirculation is less than ideal, but is offset by the larger fans and heatsinks for a typically quieter and cooler solution. The fans can be larger because they are blowing on the larger side/cross section of the heat sink. Pass through are a somewhat newer variant of open air coolers common on newer Nvidia cards that push or pull air through a heat sink that is not blocked on one side of a pc so air flows though the heat sink with less back pressure for more efficient dissipation at the expense of a more compact PCB to put all the GPU components on