The density of parked vehicles has been increased, meaning more vehicles will spawn at the roadside/parking garages. The police/amry won't respond to criminal activity or trespassing, you will lose your wanted level very quickly. This is optional, depending on which edition you download. You can shoot/see through objects such as Walls, Trees, Hedges, Bulletproof Windows/Glass, Wooden/Metal Fences).
The size of explosions (RPG, Grenade, Petrol Pump, Sticky Bomb, Tank, Lazer/Buzzard Missiles)