I appreciate the effort, but I think you missed what I'm actually asking. Knowing that an asst-man can be assigned the exact same responsibilities as a coach, is there any reason to make a coach an assistant over a regular coach?
The difference is not their responsibilities. I set the responsibilities AFTER I hire them. There is no such thing as "assistant manager" and "general coach" responsibilities. I hire them as a coach or an assistant manager, then I assign responsibilities.
In English leagues, you can only sign one assistant manager so it doesn't really matter what the difference is. In German leagues, assistant managers and coaches come from the same limit pool, meaning you can sign 10 assistants and 0 coaches or 10 coaches and 0 assistants. So the question is, why would you hire one over the other, which you finally did with your very last sentence.