The technical aspects of the features are far more similar than the quality of the film itself. Both are English DTS-HD Master Audio 5.1 tracks and the Poledouris score (he worked on both films) comes across beautifully in each. The dialogue too is clear and the surrounds really help situate the viewer. There are definitely moments when a sword hit or a punch or some other effect doesn't feel to carry the weight that it should, but those sounds seem more attributable to their conception rather than their presentation. It is clear that work has been done with the visuals on each as these are nearly 30 year old movies and they are virtually scratch and blemish free. Darkly lit scenes in Destroyer have a tendency to have more noise than they do in Barbarian and are at times distracting, but the sweat on Arnold's muscles glistens and beads beautifully. As seems to be the case with so many films, more work has been done on close-ups, to make sure that the detail on the actors are good, rather than in long shots which does lead to something akin to a grainy flicker at times. There is, in short, little to not like about the transfers.
While I certainly feel it possible to recommend Conan the Barbarian to fans of the genre (or the works of the Governator), Destroyer is one of those movies I see being purchased for completion's sake rather than because people want it for its own merits. Conan the Barbarian is bloody good fun, Conan the Destroyer is a semi-bloody bore.