Why are the right and left lungs not identical?
The right lung is shorter than the left by 1 inch (2.5
centimeters) however, the total capacity of the right lung is
greater than the left. The right lung has three lobes, the left
lung has two. If you need to know the "why" then its simply in the
human genetics that your lungs will never be identical unless you
suffer from a mutation of the genes