According to Universe Today, Venus is often called a sister planet to Earth because both planets share a number of physical similarities. They have a similar size, mass, density and volume and may have formed at around the same point in the solar system's history. While they share some similarities, Venus and Earth are also vastly different in many important ways.
Earth and Venus are both terrestrial planets, formed out of rocky elements and metals left over from the formation of the sun. Venus has a diameter of about 7,500 miles, making the planet approximately 95 percent as large as Earth. Venus has approximately 82 percent of Earth's mass and 91 percent of Earth's gravitational force.
At some point in Venus' history, however, its development diverged from Earth's. Venus' planetary crust solidified, ending plate tectonics and reducing the ability of the evolving planet to sequester carbon. This led to the development of an incredibly dense atmosphere, and the surface pressure of Venus is 92 times greater than that of Earth. Its temperatures are also much higher, averaging 860 degrees Fahrenheit. Venus also rotates very slowly in the opposite direction of the Earth, meaning the sun rises in the west every 243 Earth days, according to the European Space Agency.