Hi, I am also in Oregon. Those two accounts are separate. The IAP account is connected to your PERS account, while the 457 plan is an OSGP account. Even though they are both administered through the same office - they are not the same type of account. When you retire, you can combine them, but while employed, they are two separate types of accounts.
One is your pension (IAP counts as part of pension)
457 is an investment account.