You can't seamlessly travel from the planet's sufrace to an orbital space station and then pilot a fighter into a black hole, or chop down every tree in the world in order to gather enough wood to build a bridge to the moon. It's a game that allows you to do anything, though not in the way that a massive open world life-sim might promise. The philosophy driving the original Original Sin was based around player freedom.
At the foundations, there's a more interesting world, with a stronger set of characters, but there are also improvements to combat, and the smartest twist on cooperative multiplayer that I've seen since Dark Souls. I spent an evening playing the sequel a couple of weeks ago and it improves almost every area. It's a systemic toybox with the skin of a fantasy RPG.
Divinity: Original Sin is one of my favourite games of recent years.