They weren't the same. Divine Divinity was open world, Divinity 2 was more linear.

In Divine Divinity, once you crossed the bridge into the Farmlands, you could go almost anywhere in one of three big maps. You might be easily crushed by enemies 30+ levels higher, but you could walk there.

In Divinity 2, it was more linear. You were stuck in the north of Broken Valley until you advanced the main plot a few stages. After that you could go anywhere into the valley. You could walk into Orobas Fjords, but there was little point because a barrier kept you from walking or swimming to Champion harbour. Your only recourse was to advance the plot to open up the Maxos Temple, then to Sentinel Island, and then to reach the battle tower. Once you had Dragon form it was a bit more open world, but the game was much more linear than Divine Divinity. That's not necessarily a bad thing, though.