The Sun is almost, but not quite, perfectly round. Technically it is an oblate spheroid with an ellipticity of 9 times 10 to the minus 6, a tiny amount.
An elliptical orbit round the Sun.
The Earth goes round the Sun in an elliptical orbit, once every year, and this produces the four seasons.
In an elliptical orbit. E.g. not entirely round.
The Earth goes around the Sun in a path which is an ellipse. It takes about 365.25 days to go round once.
At it point of aphelion in its elliptical orbit Round the Sun. This happens on the 4th of July each year. At this moment the Sun - Earth distance is 152,102,196 kilometers.
Oval.
The Earth has an elliptical orbit around the Sun.
Yes, the distance from the sun is variable for anything with an elliptical orbit.
Because the Earth travels round the Sun in an elliptical orbit and at present the closest approach the Sun during that elliptical orbit occurs during the Northern winter. However precession of the axis of the Earth's rotation means that in about 12 thousand years time, the closest approach will be during the Northern Summer.
Each planet moves in its own elliptical orbit round the Sun, then and now.
Elliptical orbits of the planets around the sun actually match what we observe. Newton's Theory of Universal Gravitation states that planets will move around the sun in elliptical orbits.
Neptune orbits the Sun (as do most planets) with an elliptical orbit. When the orbit takes the planet closest to the Sun it is moving faster than when it is furthest from the Sun when on an elliptical orbit.