See the website for more info and screenshots. In terms of how they play, Rockstar say the games have a GTAV-style controller layout, improvements to targeting and lock-on aiming, an update minimap, improved radio and weapon selection wheels, and other bits. In terms of how they look, Rockstar say the games have upgraded character and vehicle models, new high-resolution textures, increased draw distances, a rebuilt lighting system, and improved shadows, weather, and reflections.
The three games have been rebuilt in Unreal Engine by Grove Street Games, the studio who previously did mobile ports of the three (and were formerly known as War Drum Studios). And probably more relevant is improvements to how they play. Curious, no? The games look newer, absolutely, but the contrast between high-tech shine and stylised art is odd and I'm not sure I'd say I think they look better.
