Avengers: Endgame - What We Got Vs What Was Advertised
3. The Major Character Differences
That obfuscation leads to a lot of differences within certain characters compared to what we'd been led to expect. Professor Hulk had been heavily theorised, so that wasn't much of a surprise if you'd spent months obsessing over the film online, but to general audiences it's a big reveal, and there's still a difference between speculating it'll happen and fully seeing it in action.
The other major character arc they completely hid was Thor: the trailers only slightly hint at his trouble dealing with his failure to kill Thanos, whereas that forms the crux of his arc in the movie, with another twist too. As completely hidden by the trailers, the Thor five years in the future has, well, he's let himself go a bit. I mean, he's still Chris Hemsworth and so yes, you still would, but he's not rocking that God of Thunder physique anymore. "Lebowski," as Tony Stark puts it, is a perfect description, but it goes beyond appearance: this is a Thor who is suffering from PTSD and has lost the huge confidence he had after Ragnarok, but responds to that in a way that isn't the moping or quest for vengeance expected. It may not be all that well-handled in the film, but it is very different to what was anticipated. While Captain America and Iron Man's arcs were reasonably clear going in, at least in a vague sense, that wasn't the case with Thor.
Then there are two of the most powerful characters in the MCU: Captain Marvel and Thanos. The arrival of Captain Marvel was massively hyped by the post-credits scenes of both Infinity War and then her solo film (both of which effectively count as marketing for Endgame), while her introduction was a big deal in the trailers too. In the film, however, she goes on the first mission, and then almost completely disappears from the story until late in the final battle, when she returns to help save the day.
By contrast, Thanos was hardly in the trailers, and yet he is still the main antagonist of the movie, but again with a twist: the Thanos of Infinity War is killed off shockingly early, and we then spend the rest of the movie with the Thanos from Guardians of the Galaxy.