big price difference on kbb.com and edmunds.com

I am planning to buy a 2004 Toyota Sienna 5dr XLE AWD, 53000 miles

I tried to find the price on kbb.com and edmunds.com and found the price is shockingly different

 

Edmunds.com showed the private party price is $11,779

http://www.edmunds.com/toyota/sienna/2004/tmv-appraise-results.html

 

but kbb.com showed the private party price is $16,260

http://www.kbb.com/used-cars/toyota/sienna/2004/private-party-value/pricing-report?condition=good&id=3554&equipment=136319|true&mileage=53000

 

I can not under stand why the difference is $5000.

Can somebody help which one can I rely on?