The 5-CD set released on Edel Classics is the same music, recorded in the mid-70s for Eterna. Regardless of label, it's such wonderful music-making!
Rösel does a masterful job of balancing the extroverted, Schumann-esque "Romantic" elements with the meditative, inward, and melancholy aspects of Brahms' music. As a result, his readings of the early works in particular are more fully realized -- make "more sense" -- than other versions I've heard.
I wonder: Would Rösel would be a more familiar pianist if he'd spent the early part of his career in West Germany rather than East Germany? Did being behind the "Iron Curtain" hamstring his opportunities for recognition in the "West"? Then again, Rösel's strengths aren't flash; it's his interpretive subtlety that's so astounding. And that's not exactly a quality that gets concertizing pianists noticed. Who knows?!?! The East/West thing may not have made any difference.