I think the key difference is that a founder has a much better understanding of the company as a complex system. This understanding includes not just how people think it works at a certain point. It includes all the previous attempts, reasoning behind those attemps, the context of past failures and successes, the personal dynamics behind those choices.
Complex systems are notoriously hard to understand. Seeing the system develop from zero to complexity is an experience and perspective that is impossible to replace. Even most early employees don't have a comparable understanding.
Of course not all founders know everything about all the key components of their businesses, but the founding team does have a much much better understanding than other person. I think that's why founders get frustrated with ineffective things. While most others have to account for unknown unknowns and give others benefit of doubt, the founders have a much better and robust understanding of why things happen the way they happen.
The difference between management and leadership may be more about where you focus and how you engage others. Being a founder and being a leader is different in how well you understand the system.