What is the difference between a smart phone and a regular phone?

I am shopping for a phone and I am noticing that many "cool" phones (phones with touch screens, full keyboard, etc) say that they are smartphones. I am wondering what the difference between a smart phone and a regular phone. Thx!|||A smart phone is usually a PDA phone that has many functions such as a Blackberry, Iphone, Instinct and others. Some have windows mobile and others have there own proprietary OS. Regular phones do internet and stuff but smart phones do it better and you can add applications to smart phones where it is harder to do to a regular phone.|||A smartphone, has more features, then a regular phone, for exampel, a smartphone can hold so much more memory than a regular phone. A smart phone may also have a full keyboard, or a suretype keyboard (2 letters per key) Smart phones also have better ways of accessing the internet, with way better browser. Smartphones are mostly used my corporate people. some smartphones are, blackberrys, palm treos, palm centeros, pantech duo, etc.|||I am sure that it is because smartphones have an Operating System.|||smart phones are smart. and regulars are dum.|||a smart phone isnt you