The most important thing is the different modes of production. Britain was the rise of bourgeois revolution and finally compromised with feudal forces. However, the bourgeoisie dominates and the bourgeoisie has the final say. The king is just a title and has no real power. For Britain, this is from the bottom up. The constitutional monarchy in Germany is that the German emperor carried out top-down reforms or unified the country by force in order to achieve national reunification and make the country rich and strong, which indirectly developed domestic capitalism. A unified country and a unified market are conducive to the rise of capitalism. Although the German emperor did what capitalism wanted to do, Germany actually entered the capitalist society. Although the emperor has real power, the German emperor is only the last feudal remnant, and finally his rights will be taken back. It's only a matter of time.