Is pioneer harness and kenwood harness the same for the radios?

I have a 2001 Pontiac grand am gt and it came with a kenwood radio in it. however my old car had the pioneer radio in it but when i went to see about getting the two switched they said that after year 2000 everything went electronic and the harness would be around $100. So i got to thinking and since the kenwood radio isn't my original radio in the car wouldn't whoever have put that in had to buy the harness for it also and if so then can't i just switch the radios? Is the harnesses used for kenwood and pioneer interchangeable? So if they are i would be able to just get the two radios switched right???