A chorus, as I’ve always understood it, is repeated more often, usually after each verse. As pulykamell says, you could analyze “I can’t help falling in love with you” as a brief chorus or refrain if you wanted to, although I’ve never thought of it that way. I don’t consider “Can’t Help Falling in Love” as having a chorus.
This song form is called AABA, A representing the verse melody, and B the bridge melody. This structure is hugely common. You’ll find it all over classic Broadway, pop, rock, country. In practice it’s more often AABABA, because the bridge and final verse will usually be repeated. Oftentimes they’ll squeeze in a guitar solo somewhere, too. 
Some songs have both a chorus and a bridge, some don’t.
By contrast, think of the Beatles’ “Let It Be.” That’s a traditional verse-chorus structure, where each verse has different lyrics, and each one is followed by a chorus with the same lyrics (“Let it be, let it be…”). This song doesn’t have a bridge.
I leave it to others with more professional musical experience to either correct or expand on this–I’m strictly an amateur–but that’s my understanding.