Cyborgs Vs. Robots

There are many movies that involve both cyborgs and robots, but some make the line dividing the two very ambiguous. Here are some examples: The “cyborg”/main character from The Terminator is nothing more than a machine with synthetic humanistic features, but is still considered a cyborg, where the robots in the movie I, Robot are machines that have features relative to humans but are not meant to look exactly like humans. What makes the Terminator a cyborg, but the machines in I, Robot robots? is it because the Terminator looks human eventhough he is not? Do the internal or external features of these characters define what they are?