The orbit around the Sun while elliptical is almost circular. Closest 91million miles, furthest 94 million miles.

The coldness during winter is due to the tilt of the earth more than a minor change in distance. Seasons change because of the tilt of the Earth which orbits the Sun about a tilted axis of 23 degrees.

During Winter in the North, the North Pole is tilted away from the Earth so the North has less direct rays from the sun while the South is tilted towards the Sun with more direct rays causing Summer.