The following are the differences between the pulmonary artery and pulmonary vein: Point of DifferencePulmonary ArteryPulmonary VeinFunctionIt carries deoxygenated blood from the heart to the lungs for purification.It carries oxygenated blood to the left atrium from the lungs.Blood natureIt carries deoxygenated blood consisting of more metabolic wastes and high carbon dioxide concentrations.They carry oxygenated blood with more oxygen and less metabolic wastes.AnatomyIt is connected to the right ventricle of the human heart.It is connected to the left atrium of the human heart.NumberThe pulmonary artery branches into two parts- the left and the right pulmonary arteries.There are four pulmonary veins present in the body, two veins in each lung.