An antagonist is a character that works against your protagonist, whilst an antagonistic force is something non-human that works against your protagonist.
There are different types of antagonistic forces, and many films have both antagonists as well as antagonistic forces.
Character vs. nature
Good survival films often pit human characters against nature, where 'nature' can come in many forms. There are too many films to mention where characters are confronted by natural disasters such as tornadoes, super storms, tsunamis, volcanoes and the like. But nature as an antagonistic force can include characters simply trying to survive the elements, and there are many films about humans trying to survive harsh environments such as jungles and deserts.
Character vs. animal
Think films like Jaws or Jurassic Park, both films where animals threaten the lives of the characters. Lots of horror films like to pit characters against unnaturally large or vicious animals, as do thrillers like The Birds.
Character vs. the supernatural
Anything that involves ghosts, demons, vampires, werewolves or any other supernatural force a protagonist must face or battle.
Character vs. society
Often the society characters are pitted against are ones set in the future, but there are many films set in the past and contemporary settings where characters battle societal oppression. This could be in the form of racism, poverty, or unjust laws. It could also just be about a character who doesn't fit in with the society around them for other reasons. They could be an outsider, or simply hold very different views to the majority of people around them.
Character vs. themselves
Often characters have to overcome themselves in order to reach their goal. This is where you make your character their own worst enemy. A good protagonist should have a flaw that slows them down anyway, but setting up the character as the main antagonistic force takes it to a whole new level.
Character vs. technology
Often the kind of conflict we see in science-fiction films, where the technology that was supposed to help humankind poses a danger. Or, the technology created by humans turns against them.
By yourself, in a pair or even a group, brainstorm as many examples of films you've seen that fit into the above categories. From the list you create, can you see any that fit into more than one category? Do any of the films on your list include an antagonistic character as well as an antagonistic force?