How is our atmosphere different from the atmospheres on Venus and Mars ?

Explanation

We know that energy is being continuously emitted by the sun. This energy is in the form of electromagnetic waves and in the form of stream of fast moving charged particles. Shields are developed around the Earth to filter incoming energy like we know about the ozone layer. (Note: Ozone layer filters ultraviolet radiations and also converts them into thermal radiation to throw towards Earth). Similarly, magnetic field also acts as a shield for fast moving charged particles shot by the sun, towards Earth. The magnetic field of Earth turns away these particles to save us from undesirable effect. Since the particles are charged so the magnetic field of Earth gets distorted too in this process. This distorted magnetic field is called the magnetosphere of Earth. Venus and Mars do not have significant magnetic field, and this may be one of the many reasons, behind no life there.
On one hand magnetic field is a saviour but excessive magnetic field again might not be desirable for the life to get flourished inside it. We should be aware that other planets beyond Mars (e.g. Jupiter) have a very high magnetic field around them. Many times things are needed just appropriate, not less and also not more than a prescribed limit.