Originally Posted by chumpsteak
Probably just the way the bottles pour. The grolsh bottles can't hold better pressure, you're only talking 12 psi. If the regular bottles couldn't hold 12 they'd be flat.
It takes a lot more than 12 psi to carbonate a beer.
At room temperature (70 deg), you need 29 psi to carbonate to 2.5 volumes of CO2, and 37 psi to carbonate to 3 volumes.