Notes:

The simple explanation to this is that the Japanese originals were called "Pokemon Red and GREEN" instead of Blue. Blue version, in Japan, was an alternate game released later. When localizing the games, the developers decided to merge the three together and created "Pokemon Red and Blue".
It's also worth noting that Japanese occasionally uses the word for "blue" to mean green: e.g. green leaves → "blue leaves", or green light → "blue light". However, this is completely unrelated to this Differenze Linguistiche.