It'll be the same game.
Don't expect new driving physics, revamped car/garage system, better police AI, interiors, or anything like that.
It's a remastered version so all that means is higher res, hi-res textures, higher fps, AA, better draw distance, higher density peds/vehicles. Yes there will be new wildlife, better destruction physics and better weather system. that's reasonable. that's the sort of stuff that they probably wanted to include in the PS3/360 versions but simply couldn't because the hardware wasn't powerful enough. PS4/XB1/PC allows that sort of stuff to be added.