The Ash Twins Blog

http://hubpages.com/hub/what-are-the-differences-between-shipping-with-UPS-and-FedEx_:

I was selling online and shipping different items, including very heavy, and here is the golden rule for all of your shipments: everything that is going out in a box, will be cheaper to send via UPS. Everything bulky, heavy and that is going to be shipped in custom package – save your money and ship via FedEx. Now, a couple of examples: Zappos uses UPS, Amazon – UPS for books and for other big items FedEx, a bundle of moving blankets would be shipped by FedEx, but a set of moving boxes – by UPS. Hope it saves you some money:)