... only marked Caesars. There are several casinos that use Caesars in their name. Caesars Tahoe, Caesars Atlantic City, Caesars Indiana, Caesars At Sea and Caesars Palace.

I'm not sure of dates but, at some time Harrah's acquired most, if not all, of the casinos above. Harrah's then changed the corporate name to Caesars Entertainment, now Eldorado Resorts. About the same time, I noticed that items were showing up with just Caesars on them. I have no evidence but, my opinion is that items with just Caesars on them were available at all or most properties with Caesars in the name. Probably a cost cutting measure. Rather than produce items specific to each location, Caesars could refer to any location.

Personally, I only collect items from Caesars Palace. Must say Caesars Palace, or 1966, or a picture of Caesars Palace, or Las Vegas as the location on the item.