Rust: What is the difference between Box<T> and Rc<T>?

Box<T> — single owner, heap allocation. Rc<T> — reference counting, multiple owners.

Box<T>:

• Single owner.
• Heap allocation.
• Drop when owner drops.

Rc<T>:

• Multiple owners.
• Reference counting.
• Drop when last ref drops.

1// Box
2let b = Box::new(5);
3let b2 = b;  // Moved
4// println!("{}", b);  // Error
5
6// Rc
7use std::rc::Rc;
8let a = Rc::new(5);
9let b = Rc::clone(&a);  // Cloned
10println!("{}", a);  // OK
11println!("{}", b);  // OK

Key: Box for single ownership, Rc for shared.