Is it even possible for Germany and Italy to treat France post-war the way that the USA treated the CSA? Germany and Italy can only take so much "border" areas. Germany isn't taking Paris, probably Alsace and the most that would be wanted riverwise is to push France off the Rhine which functionally equals taking Strassbourg. (Which as far as I can tell had been French since 1681) Italy grabs the pre Plombières Agreement borders including Nice/Nizza and (possibly) Corsica. Post war boundaries with what is now AH are going be *far* more fluid and will largely depend if an independent Hungary is at the table.
In terms of the various fronts of the CEW compared to the GAW. No state is as unprepared as the USA was. FG, FI & IA will look a lot like the war east of the Appalachians, but if the USA had 5 Divisions in Maryland on alert on day 1.
GA will be sort of a cross between the Midlands front, the mountainous edge of the Eastern Front and the Ozarks. There will be nothing equivalent to the Western Front, Mesopotamia (Brazilian/Argentine) or Chile's fighting. The equivalent to Nashville is *probably* Prague.
(Possibly also Bratislava) The equivalent to Chile is Denmark is with less war stupidity. The equivalent to Britain is... Britain. The most likely powers outside of Europe to be courted are Japan, Mexico and Brazil, but with only Japan greater than a 25% chance, I think. *Lots* of efforts to recruit experienced troops from the GAW to the CEW, with the *most* recruited being Pilots and *anyone* involved with the breakthrough at Nashville or any of the advances in the East. I don't remember where the Colonel(?) in charge of Section R ended up, could make the US lean the other way.
Navywise, you'll have Naval fighting away from Europe including the Southern Caribbean and Asia. Japan joining one side or another will make far more difference than it did in Our WWI.