the left ventricle is closer to the rib cage and therefore needs extra cushioning to protect it.

the left ventricle must pump the same amount of blood as the right ventricle but must do this at a much higher pressure.

the left ventricle must pump oxygenated blood, which requires more energy than pumping unoxygenated blood.

the left ventricle must pump much more blood than the right ventricle so it must have stronger walls.