For example, the Takeda Clan has rider more powerful than the other factions (it's historic)...
The Uesugi Clan is a clan with very good archers...
The Oda Clan has samurais with a better moral than others samurais
The Shimazu Clan has weapon more powerfuls
The Imagawa Clan has better ninjas, and better katana
The Mori Clan has the very goods Sohei Monks
The Hojo Clan has better armor

All this difference are historic, and it offer an very good gameplay, because for won a battle, you must use the strong points of your army...

PS : Have you received my PM, Intranetusa ?