Why is there such a huge price difference?

Http://www.google.com/products/catalog?hl=en&q=iphone+4s&psj=1&bav=on.2, or.r_gc.r_pw.r_qf.&biw=1366&bih=667&um=1&ie=UTF-8&tbm=shop&cid=14315240828277841715&sa=X&ei=FvA8UMmLHYzS4QTJ5YCICw&ved=0CLABEPICMAM

http://wireless.walmart.com/content/iphone/#product_details?povid=cat14503-env172199-moduleB082512-lLink_MGW_IPHONE
please someone tell me what's happening?

The phone on google is for the phone only -- no wireless contract.

The phone on walmart is for the phone with a wireless subscription.

When you buy a phone outright (such as via the google link you provided), you pay the full retail price.

When you buy a phone with a plan (such as via the walmart link you provided), the wirless operator subsizes the cost of the phone, thus reducing the initial purchase price of the phone. Over the course of the service contract, the wireless operator makes back the money they fronted you on the initial purchase. That is why there's a large penalty associated with terminating a wireless contract prior to the end of the contract period -- the wireless operator is recouping the money they advanced you during the intial purchase of the phone.