We've now got enough of the game's UI and gameplay through the 2018 E3 trailer that I think we can start speculating on what we might see that is new.
One obvious thing that stands out is that Naughty Dog are adding special ammo crafting to the game, much in the style of Tomb Raider or Horizon Zero Dawn. We can see Ellie crafting an explosive arrow (and its effectiveness). We also see a modified UI that seems to show full health as being only half the HP circle. I'm wondering if that is a hint that armour crafting might be on the cards too.
That aside, the gameplay was very much in the style of the first game apart from a changed aiming reticule for the bow.