[jcranmer]

I've been of the opinion that it's simply easier to analyze the era from ~1914-1945 as one long era of war with ill-defined boundaries of conflicts, rather than looking at WW1, Russian Civil War, Spanish Civil War, Second Sino-Japanese War, WW2, and a host of other smaller conflicts (including Continuation War and the Second Italo-Ethiopian War).

As a practical matter, the European/African theater against Germany/Italy and the Pacific theater against Japan are two separate wars that happened contemporaneously and with some powers fighting the two wars at the same time. The Continuation War was in large part pushed by the Germans to extend the front of the USSR, and as such is essentially part of the Eurafrican WW2, although the Finns did not entirely cooperate in actually pursuing Axis objectives.

This does show the difficulty of drawing firm boundaries around the wars in this era.