Neptune is the farthest planet from the sun and has an extremely wide orbit and a comparatively slow orbital velocity. Because of this, Neptune has a very long year. It is approximately 165 times the time of a year on Earth.
Saturn orbits the sun at about 9.5 AU, which is nine and a half times the distance between Earth and the Sun. Because of this, the speed at which it orbits the sun is considerably slow. Saturn's year is about 29 and a half Earth years.
Mars and Earth are very close in many ways, except for the length of a year, they are very different. A year on Mars lasts almost two times the length of a year on Earth. This is because Mars is significantly farther from the sun and its orbital period.