There are two major differences between smart phones and cell phones: smart phones can run applications and cell phones can’t and smart phones can access the Internet directly, unlike cell phones which rely on a carrier to get you there.
Most people by now have seen or at least heard about smart phone applications; the most popular of which are of course those for the Apple iPhone. The reason smart phones can run such applications is because the makers of these nifty little devices have added both hardware and software to run those applications, which means they have a CPU, memory and all the other stuff that allows personal computers to do the same thing. But because they are so tiny, special versions of all these tiny hardware devices need to be developed specifically for them. In addition to the proprietary hardware, smart phones also run specialized versions of software, instead of say, regular old Windows that everyone already knows and loves. This is why most applications for smart phones, only run on the phone they were written for. And because the makers of these devices made certain parts of their phones internal workings available to the public, other people were able to write applications for them which were then made available to everyone else via proprietary store fronts. None of this is possible with regular cell phones.
In addition to their ability to run applications, smart phones are also able to access the Internet directly. This means when users use their smart phone, they are connected directly to the Internet, rather than having to go through their carrier. Regular cell phones can perform Internet activities only by sending commands from the phone to carrier, which the carrier than passes on to the Internet, and then vice-versa for receiving information back.
The reason smart phones can access the Internet directly is because in addition to using the well known cell towers to transmit the telephone calls, they also connect to other wireless towers to send and receive information directly to and from the Internet. This is why the smart phone carriers charge separately for cell phone and Internet services on their devices, because they are in fact, two actual separate activities that appear as one when a person is using their smart phone. It’s also the reason that smart phones sometimes have more problems with dropped calls than do regular cell phones, because they have two transmitters and two receivers and then to avoid the two interfering with one another inside the phone, engineers had to build in little firewalls to keep the two signals apart.
Also, it might be noted that all the noise you hear about on television where one carrier is boasting it has G3 or G4 or whatever, only applies to the Internet portion of the phone, because the cell phone part of the phone still uses the same hardware and towers and protocol as do regular cell phones.