The second model has a smaller 27-inch display, 2560×1440 resolution and 350 nit brightness.
Leaving the specifications aside, their main news is the response time of 1ms and the refresh rate of 144Hz for the small model up to 175Hz for the big model.
Both are compatible with Nvidia G-SYNC technology. There is still no news about the price but are not going to be cheap. LG said orders for the 27-inch model begin on July 1st in the US and Europe at the end of the year.