Suppose a mad scientist went back in time to the beginning of the solar system and caused the newly formed Mars and Venus to switch places. So now there is a Venus-sized planet where Mars was (let's call it Venus 2), and a Mars-sized planet where Venus was (let's call it Mars 2). How would these hypothetical new planets, Mars 2 and Venus 2, turn out in this alternate time line

Mars2   illuminated side of the planet is very  heat, dark side very cool

Venus 2 a warm planet with a constant temperature across the entire surface

Explanation:

For this hypothetical case, when changing the planets they are changed with their current characteristics.

Case of Mars2

In this case, there is a planet with a very thin atmosphere, so the solar radiation reaches the ground without damping it, causing a lot of noise, so the illuminated side of the planet is very heat and when the dark side turns due to the little atmosphere it loses everything the heat for which it is very cold.

This thermal stress between the two sides of the planet continues constantly creating possible fruit trees in its rocky systems.

Case of Venus 2

The planet has a high atmospheric density, but it is very far from the sun, so the amount of radiation that arrives slightly warms the planet, but due to the thin atmosphere the losses for the dark period are very small, so the entire planet it is heated until it reaches an almost uniform temperature over its entire surface.

In this case we have a warm planet with a constant temperature across the entire surface, regardless of which side is lit.

-4 on