Confronted with these two boxes side by side at the store, I was forced to buy them both for a Zinger-Off.
The Zingers look identical, but the Dolly Madison box claims their Zinger is filled with "créme" filling while the Hostess Zinger is filled with a "creamy" filling. The Zingers seemed to taste very similar although I thought the Dolly Madison filling was more grainy than the Hostess. Erin felt the Dolly Madison cake was a bit dry in comparison.
Then I took a look at ingredients. They're exactly the same (both equally unhealthy). Also they're made in the same Kansas City factory. I guess a Zinger is a Zinger, no matter what the brand name. One concrete difference though, was that the Hostess version was slightly more expensive per ounce.