"Built this a few days ago shortly after building the Y-Wing from Rogue One (75172) so I could account for the differences. They are meant to be different variants or models of the actual Y-Wings depicted in the movies, and I think Lego did a good job with ensuring that these two models were in fact different. The Resistance Y-Wing is viewed as a sleeker more symmetrical variant, whereas the original was not. This one is definitely much more sleek, and I feel that Lego did the best they could without having to create new elements to make it more movie accurate. From a build standpoint; the bomb bay is slightly different, the nacelles are different, and the cockpit/nose shows the greatest difference with elements used. The model is longer and taller than the Rogue One Y-Wing. It is a very sturdy model that can be played with and I feel it is different enough in terms of how it is built from the Rogue One Y-Wing that it is a good one to have for any fan.
Please note that the picture shows the models without their stickers. I like to keep my options open ;)"