No difference, Oberhofmarschall sounds more grandiose, that's all. There's an amusing interlude when the court is evacuating Berlin the second time, Amalie takes old Pöllnitz along in her carriage because no one else is offering a place in the hectic mess, and Lehndorff regards this as a proof no good deed goes unpunished because Pöllnitz promptly appoints himself Amalie's Oberhofmarschall (she doesn't have one since doesn't have a large enough Household of her own), to which everyone goes "oh no you're not!" (Wartensleben, too, of course!)

So: what was a type like Ludwig the sugar hoarder like as a young man, and was Fritz promoting or punishing him when making him his unwanted wife's Oberhofmarschall? Also, how come Grandpa Wartensleben, who was a baroque splendour guy, had such a cheapskate son? Then again: F1 had FW!