Portable backpack back

What is the difference between Sim City 3000 and Sim City 4? - sim city 1.1.638

So I used to have, Sim City 3000 and has a lot of time and want to buy again. It seems more difficult than yesterday. I see a Sim City 4 and I just wanted to know if there is a difference, or if you prefer over the other. All comments are welcome.