Why is there a severe difference in the climates of Northern and Southern Hemisphere?

Why is there a severe difference in the climates of Northern and Southern Hemisphere?

شمالی اور جنوبی نصف کرہ کی آب و ہوا میں شدید فرق کیوں ہے؟
Explanation

These are the rotation of the earth around its axis and the revolution of the earth around the sun of its orbit.