The following paper is a comparative analysis of high speed rail in Poland and in Japan. Ulrich’s product architecture was used for this purpose along with its extension created by Takahiro Fujimoto. Based on the secondary data analyses, significant differences in high speed rail systems in Poland and Japan were found. The aim of this paper was finding the reasons behind the abovementioned differences. The answer to that question was found with the theory of product architecture and Product Architecture Matrix, used in the context of complex services. After analyzing theory and examples of Poland and Japan, it was concluded that in case of high speed rail, integral product architecture outperforms modular product architecture.