8000 – shockproof to 2m**, waterproof to 10m***, crushproof to 100kg**** and freezeproof to -10°C
6000 - shockproof to 1.5m**, waterproof to 3m*** and freezeproof to -10°C
these are the main difference I based the decision on not spending the extra $100 you pay for the 8000 on... I might regret not spending the extra $100... I figured we won't be snorkeling or scuba diving anytime soon with our youngin's... in a few years, I'll get the latest and greatest when we're able to travel more... so go for the 8000 if you see vacation time in your near future...
this link might help out... I just googled it...
Olympus unveils Stylus Tough 6000 and 8000: Digital Photography Review