Rust: What is the difference between Cell and RefCell?

1use std::cell::{Cell, RefCell};
2
3// Cell
4let c = Cell::new(5);
5c.set(10);  // No runtime check
6let val = c.get();  // Copy
7
8// RefCell
9let r = RefCell::new(vec![]);
10let mut borrow = r.borrow_mut();
11borrow.push(1);
12drop(borrow);