. . . they are more similar than not, starting with dimensions (both 12.5 "', movement height was shallower in the UG 215 by .10 mm at 4.10 mm vs 4.20 in the Buren 1000A) and with very similar bidirectional winding systems that were the subject of a patent dispute (of which Tony C knows in depth). Some minor technical differences include the additional shock mounting of the escape wheel in the UG, the use of a screwed balance in the Buren as opposed to a ring balance with UG, and tuning differences (UG came in both 2.5 Hz and 3 Hz varieties, Buren at 2.5 Hz) - also, some UG models had whiplash regulators. I found a reasonably priced UG Polerouter a few weeks ago at a local second-hand watch store that came with my favorite iteration of the UG series of movements, the 218-9 with whiplash regulator, but it had a second set of springbar holes drilled in the lugs so I decided to pass . . . it was otherwise in quite decent shape, with original dial, hands, and crown, and a respectable amount of wear on it's gold-capped case. Cordially, Art