chairman is the biggest in a company. he's the one who approve your paycheck every month, doesn't do anything much and can don't even need to be technically knowledgable in the product/service the company is selling/providing.
a CEO is the 2nd biggest. he basically runs the whole show and decides on the company policies. he need not be technically knowledgable in the product/service the company is selling/providing as well.
then below CEO we have the senior vice-president, vice-president, assistant vice-president then followed by senior managers, managers. these are the poeple must be technically knowledgable in the product/service the company is selling/providing. if not then something is very wrong.