One astronomical unit (AU) is defined as the average distance between the Earth and the Sun, which is approximately 149.6 million kilometers. Therefore, to convert AU to kilometers, we can multiply the distance by 149.6 million.
The closest Venus comes to Earth is 0.28 AU, which is equal to 0.28 x 149.6 million = 41.888 million kilometers.
The closest Mars comes to Earth is 0.37 AU, which is equal to 0.37 x 149.6 million = 55.352 million kilometers.
Therefore, Venus comes about 13.464 million kilometers closer to Earth than Mars does.