I think in the context of a restaurant, the "chef" is the one who cooks and has many orderlies to accomplish such mundane things as peeling potatoes, + some "under-chef"'s who work/cook under his orders and according to his directives. He's the one who gives the touch to the cooking of a particular restaurant, and wears the famous white hat.
On re-reading your post, I guess that you know all that already, and yes, I think the executive chef is the "boss" chef