Similarities would be
They are both made of rock.
They are close in size.
They both have thick atmospheres.
They both have similar densities.
The strength of the gravity on their surfaces is similar.
Differences would be Venus and Earth are planets in our solar system, with Venus being the second closest planet and the Earth being the third closest to the sun. The mass of the earth is about 1.23 times the mass of Venus.
Being closer to the sun, Venus is a lot hotter than the Earth. While the average temperature on the earth is about 14 °C, that on Venus is over 460 °C. . Hope that helps