MindzEye
Wayward Ditch Pig
I think it's about half an hour of new footage but not sure.
Snyder cut is almost 4 hours, Whedon's theatrical cut was just over 2 hours.
Snyder only reshot something like 10-15 minute of purely new footage for this cut after he took the project on, but there's a fuckton of material that didn't make Whedon's hatchet job and 11th hour reimagining, that we'll see in the Snyder cut. A lot of character building and backstory, a bunch of additional characters.