Blue Earth and Green Mars

Billions of years ago, two asteroids entered the newly formed Sol system containing water and bacterial life. One asteroid collided with our planet with the second colliding with Earths brother planet Mars.

Differences from OTL

 * Mars has its own species and civilization.
 * Interplanetary travel has been developed earlier in advance, becoming more expensive that air travel.
 * The civil rights movement in the United States of America was for the Martians instead of African Americans in the United States.