Polar stratospheric clouds (PSCs) play a crucial role for the stratospheric ozone layer in the polar regions. Their various forms of appearance - e.g. the state of aggregation and size of their particles- have a decisive influence on the amount of activated chlorine leading to ozone destruction. Differences in Arctic and Antarctic PSC occurrence are to be expected due to the different vortex stability and temperatures. Our study is based on PSC lidar observations from Ny-Alesund [79°N, 12°E] and McMurdo [78°S, 167°E]. As expected, we find large differences in the occurrence frequency of the various PSC types. Yet, the statistical analysis reveals some surprises, e.g. it is found that the most common PSC type at the Antarctic station is made from solid NAT particles, while only a small fraction of the observed cloud layers consist of ice particles. On the other hand, the majority of PSCs at the Arctic station is found to consist of liquid particles. As the PSC type has an influence on the heterogeneous activation rate, these results have to be carefully validated and taken into account by ozone chemistry models.