There is nothing different.
WA State Licensing: Firearms Purchase/Delivery Requirements
The CPL only affects handgun purchases. In Washington State there are two separate background checks required to purchase a pistol, the FBI NICS check required by Federal law and the local LE Agency check required by state law. With your CPL, you have already passed the LE Agency local check, so the dealer does not have to wait for that, they simply call FBI NICS and get their approval and you are good to go. Without the CPL, the local dealer does not do the FBI NICS check, instead they forward the application to purchase the pistol to the local LE Agency and they perform both their own background check AND the FBI NICS check. If both their background check and FBI NICS comes back clean, they approve the application to transfer the pistol.
Rifles and Shotguns in Washington State only require the FBI NICS check and the dealer will always perform that, regardless of CPL status.
Here are the changes in July, 2011:
None of the changes affect purchasing firearms.