The major difference between PDAs and Smartphone’s are more than just the Smartphone can send and receive calls and the PDA can’t. The PDA has a bigger screen that usually takes up the whole front side of the device. Data can be entered on a PDA by using a stylus or keys. On the Smartphone however they don’t offer on-screen keyboads. Everything is done by the buttons. If you are not sure what one is best for you maybe invest in a Hybrid version of both.