The DR/Rigid ( same optics) have more contrast and very slightly less resolution than the original collapsible.

If you were to photograph a brick wall from 20 feet with all the versions of the Summicron lenses, you would find the centers area of really good resolution wide open gets bigger with each generation and contrast goes up.

Stopped to 8.0, there is less difference among the versions.

By the way, the optical formula of the DR/Rigid was slightly changed in 1960 so the later lenses were more contrasty. The early ones have small scallops on the focus ring, and the later ones wider scallops. My neighbor always refered to the early versions as making "peaches and cream pictures".

DR/Rigids are the very same optical formula with the DR ones being mated to a different focus mount. They are all the exact same tested focal length, where the Rigids were allowed to ship if they were in the permissible tolerence range.