Mechanics and Dynamics

Today in Intro to Game Design, we discussed what dynamics are and how they differentiate between mechanics.  It's sort of a blurry line between the two, but the line is still there.  I have found myself defining and explaining mechanics using dynamics, such as defining the mechanic of in-game currency by giving the dynamic of what the player can do with the money. 
I think a good way of explaining the difference between mechanics and dynamics is that mechanics are a sort of set rules or general outline, while dynamics are how the player interacts with those rules.

An example of this our group discussed was chess.  A mechanic would be that the bishop can only move in a straight diagonal line.  The dynamic is where the in this diagonal line the player wants to move their bishop.  Do they want to take another piece or just move it into position.  Essentially, the player is using the rules of how the pieces move to plan a strategy.