The Euro-R models were Japanese market equivalents, engineered in Japan, for Japan, using the CL1 chassis.
Bizarrely, at one point Honda was selling three different cars as the Accord at once - one in the USA, one in Europe and one in Japan. There was also a time where Honda sold a Japanese and North American Accord separately to a European one, and a Japanese and European one separately to a North American one. It was insane.
The ATR came at a time when the European Accord wasn't the Japanese or North American Accord, and Honda UK just went nuts. The Euro-R followed two years later with basically the same idea but never got credited as a proper Type R. Strangely, given the 'Euro R' name, it was never sold in Europe - just as the Type R was never sold in Japan.