It’s a distinction without a difference. They were both socialism with a view toward world domination. Throw in maoism and you’ve got the hat trick.
Nazis were “national socialists”, with an eye towards a “Greater Germany” dominating Europe (they built no aircraft carriers, few heavy bombers); the Bolsheviks were determined to spread “world socialism” around the globe (and nearly succeeded). At no point in WWII was Germany a threat to the United States; even the threat from Japan was weak - within six months of Pearl Harbor they were losing the war (after Midway).