In UFF, Ben and Reed grew up in NYC - in this film they appear to be in some sort of rural town.
In UFF, Reed was sent to the Baxter building at a young age - in this film he appears to go there when he is a young adult.
In Uff, Ben was a tall, muscular football player - in this film he is a skinny, short baseball player.
In Uff, Victor Van Damme was a wealthy descendant of Dracula - in this film he's Victor Domashev and he is poor and adopted by Franklin Storm.
In Uff, Johnny and Sue were brother and sister - in this film, Sue is adopted from Kosovo.
In Uff, Arthur Molekevic was a major character who became Moleman - in this film there is no Arthur Molevic and instead we get Harvey elder which was the name of a completely different 616 character who became Moleman.
In the UFF, they didn't travel to and explore the N-Zone. The device blew up when it was turned on - In this film, a primary plot point seems to be the travel to and exploration of the N-Zone
In UFF, they weren't held captive by the government and they weren't used as weapons by the government - That seems to be a major plot point of the film.
In UFF, they didn't struggle to deal with their powers and they didn't need "containment suits" - That seems to be a major element of the film.
In UFF, Van Damme grew organic armor with goat legs and breathed some sort of poison gas and other silly crap - In this film, he doesn't look even vaguely like the UFF version and his powers seem very different.
In UFF, Van Damme went to Denmark and became leader of some group of homeless people - In this film he seems to travel to (and possibly get trapped in) the N-Zone where he poses some non-specific threat the FF must fight.
In UFF, Ben looked like the Thing, with smooth, regular plates, 3 fingers and a thumb, etc. - In this film, he's a rough, lumpy rock creature that only looks superficially like the Thing.
In UFF, BEN wore PANTS - Nuff said
In UFF, The FF wore blue uniforms
. . . to name a few quick things off the top of my head that are clearly different from UFF from the little bit we've seen and heard so far. I'm sure there's much more drastic departures in the actual film that we just don't know much about yet.