Today, I was pleasantly surprised to find the Griffin Mountain (Runequest, 1981) that arrived in the shop is the licensed UK edition by Game Workshop. I was unaware this version existed.
I first noticed the quality difference before anything else. Many (most, really) of the US edition Griffin Mountain books I’ve encountered over the years had cracked bindings, with pages either threatening to come loose, or are already loose. Chaosium’s printer used a low-quality glue that hasn’t stood up well to time.
In contrast, this Games Workshop edition is firmly bound. The paper quality seems better as well, semi-glossy.
As far as I can tell, the content is a page-for-page duplicate of the Chaosium printing.
The GW map is smaller (15½” x 23¼”, vs. 20″ x 30″ US map), and likewise of a glossier paper stock.
EDIT 12 May 2021
Griffin Mountain Poster Map (both sides): Balazar & Elder Wilds. Click for full image.