Manager vs. leader - that's a useful comparison.
In a strong economy with commerce-friendly markets like what's often the case in America, perhaps adequate management and marginal leadership is enough.
I took a course on the economic history of America where we asked why America grew to become an economic powerhouse. Marginal worker productivity wasn't any greater than England. The answer was the sheer size of the market (tied together with a unified currency and banking system, with commerce-friendly policies) made the difference. We've got an environment where it's relatively easy to thrive in business. So, we don't have to be as good at management or leadership to thrive.
I've seen a case where an American business was bought by a group from Germany - and the Germans were able to immediately manage the business better and produce more revenue/reduce costs. They may or may not have provided better leadership. I suspect the environment in Germany is such that German companies must manage their businesses well in order to survive - and so those practices are put in place.
On the other hand, I've worked for companies here in America where the management was adequate, but definitely not optimal, and the businesses did alright.