Managing Director - non USA term for CEO used in companies. The person appointed to be in overall charge of the affairs of the business, with ultimate responsibility for its performance and operation.
Managing Director - older style term used in some European countries for 'the boss'. Is the head of a business, responsible for everything - all seeing, worthy and wise. Carries the ultimate 'can' if things go wrong, but is the figurehead for accolades when success is achieved. Invariably finishes career by writing a book telling everyone else how it was done.