Ok. So I am taking ICE Hamburg - Berlin and ICE/RE Berlin/Kempten in 1st class with a seat reservation

Since I am from India I guess I will use the analogy from there. While travelling in India if you hold a particular class ticket you are assigned to a certain coach on the train and a certain seat/ berth.

So on the ice trains- are you also assigned to a certain coach/ seat or its where ever you can find an open seat.

Thanks for clarifying.