I haven't tried them yet but I do plan to do a taste comparison on the Udi's and Rudi's buns. From what I can see the Rudi's hot dog buns are smaller than the Udi's. This may be a better thing for my family since the buns seemed to be too much for my kids. The Rudi's hamburger buns don't look like "regular" buns as much as the Udi's do, if looks matter to you. Both packages contain 4 buns.
If you want to give these a try check out Rudi's webpage for a $1.00 off coupon on any of their bread.
Pictures are from the Rudi's website.