Checkout by Amazon and Amazon Simple Pay are two different levels of PayPal-like services Amazon.com quietly launched on Tuesday. No press release, no front-door promo. Simple Pay works a lot like PayPal — customers at another e-commerce site can use it as an alternative to entering a credit card number. Checkout by Amazon goes further, letting websites make use of Amazon's 1-Click ordering and allowing shoppers to put Amazon.com purchases in the same virtual cart. Previously, Amazon had required retailers to set up on Amazon.com itself. Now, the company is looking to get a piece of the action any way it can.