I don't know which Sims to get

[Earth Mama]

The main difference between the Sims 1 and Sims 2 is that in TS2 you can have sims lifecycle - They are born, grow up, grow old and die, leaving behind the new generation. You can make legacies with Sims 2.
In The Sims 1, on the other hand, you make sims and they will be forever adults. If a baby is born, it's going to turn into a kid eventually, but it's going to stay a kid forever.

Another difference between these 2 games is the graphics. While sims 1 is 2D, Sims 2 is 3D and you can rotate the camera, zoom in and zoom out as much as you like.

I strongly recommend Sims 2. IMO it's easier to play and is much better. 8)