Well....most would say say the length (the new Synder version is 4 hours long, while Whedon's version is 120 minutes.
However, I would offer this one key issue...Synder built his original version around this catastrophic event which occurred, and in a moment of great chaos...the Flash makes this decision to travel to the past and change history.
The Whedon product (2017)? It dumped this Flash moment of changing history. Why? Never explained.
The studios having a problem with DC Comics and the characters involved? It wouldn't surprise me if they viewed this whole thing (expanding out beyond Batman and Superman), and shaking their heads over the idea of things which they don't think about....mostly because they never read comics as a kid.
The 2017 version? It was just plain 'vanilla'. They had a four-hour story and chose to compact it down into 120 minutes.....just giving the viewer a simple taste of the whole DC Comics 'world'.
It wasn't bad....it just wasn't that much to get hyped-up over.
The Synder version of 2021? Well...the whole story is laid out....demanding four hours of time, and you get some passion over the characters and the story. I do agree...you probably need a 10-minute break in the middle to visit the bathroom (something that Gone With the Wind offered when it came out).
