It's commonly portrayed (in video games, and to a lesser extent in film/TV) that medieval peerage functioned a lot like modern military ranks - that is, the knight reports to the baron, who reports to the count, who reports to the duke, etc... up to the King; very ladder-like, where at each step a lord has multiple subsidiary rulers under them. Is this accurate? Is it more accurate in some parts of Europe than in others?

Let's take a concrete example: Charles IV, Duke of Anjou, owed fealty to the King of France. Were there counts, barons, or other lesser land-owning nobility who owed their fealty to Charles IV? Was the distinction even important? What about in an earlier period - the French crown was (as I recall) quite weak in the middle ages in relation to it's land-holding nobility, and counts of Berry in the 10th century appear to have waged war independent of the King. Could Fulk the Red, Count of Berry have called on vassal barons, or some other titled nobles, to levy troops and go to war with him?

I can't imagine that this would have been the same everywhere, either; what about the pre-Norman Earls of England? Or the Grafs of the HRE?