What's the real difference between 2006 model cars and 2007 model cars?  I just can't tell a difference anymore or is it just a money thing?

Really, the difference is almost the same in the bowling ball world as in the automotive world.  That 2006 car--err, ball probably has quite a few more miles than the 2007.  Last year's balls, or even 2002's ball (your Freak Out) are usually going to have hundreds of games on them.  That wear and tear will reduce the ball's performance over time.  Coupled with advances in lane oils, that medium-oil Freak Out from 2002 turns into a medium-light to medium-oil Freak Out in 2007.  

Now is there much of a difference between a medium-oil ball and a medium/medium-light oil ball?  No, not really.  You might still have 80-90% of the performance if you maintained it.  On the conditions it works on, it will hit and carry as well as it did five years ago.

Now a five year old Freak Out with zero games on it today may very well still be a good medium-oil ball, just as it was five years ago.  But it's got no wear and tear on it.

So what's the real difference between today's balls and yesterday's balls?  Over a long period of time, you'll see a diminished oil handling capacity no matter how many games you put on it.  A brand new 10-year-old ball that was for heavy oil is probably a medium to medium-heavy oil ball now.  A 10-year-old heavy oil ball with 1000 games on it is probably not much more than a medium ball now.

In the short term, there's little difference.  Two, three, or four years, there's probably not a whole lot of difference.  Five or ten years?  Now you're looking at probably a grade or two of difference in oil handling (heavy turns into medium-heavy, medium turns into medium-light).

SH

In a way, some of the new balls are starting to look like older (10 years) balls.  In the time period between, many balls were all or nothing.  Huge particle loads that gave up the ghost by 30' on anything less than a flood or super snappy pearls that took a U turn when they hit friction.  The new balls have a lot of blended combination covers that allow them to read the lane peoperly, sort of like urethane balls with stronger back ends.  You see many solid/pearl/particle covers and sometimes they don't even want to tell you exactly what they are.

On a THS, there is little to differentiate 80+% of the equipment out there.  Get on some flat patterns and you'll start to see the differences.  I still have no idea why most people go out and buy the next super bomb to bowl on league shots.  Maybe if there's a ton of money riding on a scratch league where an extra strike or two during a set might net you some cash, but otherwise, it's a waste of time and money.  The two balls you list should be fairly equal over the long haul.  On the fresh, the BWP might be too much on the back end so the FAZ might shine.  Get a little carry down, and the BWP will be a better alternative.
--------------------
Telling it like it is.