Arkane Studios has put out a trailer for Dishonored 2, showing how each level in the upcoming game will be based on a unique theme, and even unique gameplay mechanics.
Missions will still be differentiated from one another on a visual and thematic level, just as in the original Dishonored. The example of this given in the trailer is of a conservatory area, in which the player is leaping atop large taxidermy birds to make their way from one place to another. Dishonored 2 will also differentiate missions by having certain areas feature unique gameplay mechanics (and the game will also have a wider variety of endings).
In the Clockwork Mansion, players need to reshape the architecture of the level by activating numerous levers and switches. Hitting one switch may open up certain areas but also close off access to others, so you will need think ahead about where you are trying to get to and how to change the layout of the level to create a path that leads there. And in Crack in the Slab, players have the ability to jump between two different time periods, and they also have an item that will let them see what the other time period looks like at a given location before they jump there, allowing them to get the drop on enemies.
Dishonored 2 releases on November 11th on PC, PlayStation 4, and Xbox One.