The difference this time is Germany, Italy and Japan are not in a coalition against the allies. That leaves no large coalition that could fight against each other.
Don't forget Russia. That one was in coalition with the Nazi Germany since August 1939.
The huge difference was that there was a country that wanted to invade the whole world. You had Germany invade Czechoslovakia in 1938 Poland in 39 , France, Belgium and the Netherlands in 40, and so on. The only country acting like that at the moment is Russia, but it lacks the military force to do so.