The key difference between right and left atrium is that right atrium receives deoxygenated blood from the body while left atrium receives oxygenated blood from the lung.
The human heart has four muscular chambers: two atria and two ventricles. Atria are the two upper chambers of the heart that receive blood. The atrium situated at the right side of the heart is right atrium while the atrium situated at the left side of the heart is left atrium. The left atrium receives oxygenated blood from the lung while the right atrium receives deoxygenated blood mainly from superior vena cava. Then the blood flows from left atrium to left ventricle. Similarly, blood flows from the right atrium to the right ventricle. Both atria are equally important.
