Arteriosclerosis is a general term for the hardening of arteries and a loss of elasticity in arterial walls. Atherosclerosis is specifically a condition where arteries harden as a result of plaque buildup on artery walls. Both conditions result in poor and inefficient blood flow through arteries, which can lead to blood clots or ruptures in the blood vessels of the heart or brain. Blockages in the heart can result in heart attacks; blockages and ruptures in the brain lead to strokes.