The Amazon.smile site and prices are 100% identical to the regular site -- it's simply their charity arm. For me it means that I can not use my phone or iPad app to purchase -- you need to log into the Amazon.smile site via browser.
There is a one time need to set up the charity of your choice -- clicking on the banner here will take you directly there. After that it's effortless. (Amazon packages show up at my home so often that the UPS driver and my dog have become very good friends...)
If you are a household that uses Amazon frequently I strongly encourage you to use the service for your favorite Church, 501c3, or Police Dog Foundation!