[jonathan180iq]

An aggressive driver is someone who zips in and out of traffic, taking "control" of the entire road and avoids people by using speed and general ass-holery. Two cars form a block that general drivers cannot pass. The aggressive driver either tailgates and honks at the people in front of him or he flies around them on the median, hanging a one-finger salute out the window.

A defensive driver, on the other hand, will anticipate possible negative situations and/or avoid them all together.
Those same two cars are blocking your ability to pass them and get into another lane. The defensive driver will simply slow down, alter his tempo, reach a state of zen and continue merrily along, behind them. Or if you notice idiots who are texting while driving, leaning over to grab a CD from the passenger floorboard, applying make-up, or otherwise simply not paying attention, the defensive driver should notice this behavior ahead of time and stay away, thus avoiding even having to use their amazing motorcycle handling skills.