What are the similarities and differences between arteriosclerosis and atherosclerosis?

Largely None: 2 different words for aspects the same disease process. The disease (a) typically start in later childhood, is (b) due to an accumulation of white blood cells in the walls of the arteries, (c) no symptoms occur for decades, though arteries get stiffer (d) most events are without symptoms (despite tissue damage) when symptoms finally do occur, they are commonly of sudden onset due to plaque rupture.

Two similar words: Atherosclerosis and arteriosclerosis are two different words that refer to the same disease ; much like car and automobile.