Why are there differences between seasons during the year ,summer ,winter,spring and autumn?

Question

Why are there differences between seasons during the year ,summer ,winter,spring and autumn?

Answer 1

As the earth rotates around the sun your particular area is either closer or farther away from the sun.  The two site's below graphically represent what each season's position is,  relative to the sun as the earth moves in it's orbit.

Answer 2

Locally, due to changes in length of day and sun elevation resulting in changes in the intensity of solar radiation, and consequently temperature.

On a hemispheric and global scale, due to changes in the general circulation - where the sub-tropical high belt shifts to, where the mid-latitude Highs and Lows track.

In boreal summer the northern hemispere is tilted towards the sun, and in winter away from the sun. And so on.