Based on the description of "Six Easy Pieces", it appears to be a book targeted specifically at a lay audience, to popularize physics. The Feynman Lectures on P

Based on the description of "Six Easy Pieces", it appears to be a book targeted specifically at a lay audience, to popularize physics. The Feynman Lectures on Physics are basically a collection of lecture notes for a series of courses he taught at CalTech to physics majors, a decidedly not-lay audience.