On the official site of Shadow of the Tomb Raider, developers from Eidos Montreal told that in the game it will be possible to change the difficulty settings for individual gameplay elements.
The three main gameplay elements, whose complexity you can configure separately, are the combat system, the exploration of the world and puzzles. Each of the elements can be configured as light, normal or heavy – and these changes will significantly affect the game.
You can change them at any time, but there is a fourth difficulty setting, the highest is Deadly Obsession. It covers all three gameplay categories at once and can not be changed afterward. This hardcore.
A source: tombraider.square