Is the difference between OBD1 and 2 only in the ECU?

By what I've heard I'm assuming that you could have a 96 civic, get a b16 motor and have an OBD2 ecu. That ecu would wire up to the place where the DEQ plugs into your computer....?

Now if you have a 94 car, could you get an OBD2 ecu and actually hook up that shiznit? I know the DEQ wouldn't plug since the car is a 94, and I've heard that OBD2 is not the desired type because of all the sensors and bull****.

Fill me in here...