The Game Master in Divinity Original Sin 2 allows for a more customized and flexible experience compared to the main story. The GM can create unique scenarios, change rules, and manipulate the game world in ways the set story doesn't. For example, a GM can introduce new quests or modify existing ones on the fly, while the story follows a more linear path with defined plot points.
The story in Divinity Original Sin 2 is like a carefully crafted tapestry, with each thread representing a character, quest, or plot development. It's designed to engage players and draw them into the world of Rivellon. However, the Game Master vs Story is a contrast in control. The Game Master mode is all about taking the reins. You can introduce elements that completely deviate from the main story. For instance, you can create a scenario where the main characters have to face an entirely different kind of enemy or solve a problem that has no relation to the main story's plot. This makes the Game Master mode a very different and more fluid experience compared to the fixed nature of the main story.