- `final`: When you don't want to change a variable's value, use `final`. Once initialized, its value is immutable, but it must be assigned at runtime—meaning it can be initialized in constructors or other methods.

```dart
final String name = 'John Doe';
```

Or assigned at runtime:

```dart
final DateTime currentTime = DateTime.now();
```

- `const`: Use `const` when defining a compile-time constant. A `const` constant requires all values to be known at compile time.

```dart
const double pi = 3.14159;
```

You can also use `const` to create immutable collections at compile time:

```dart
const List<int> numbers = [1, 2, 3, 4, 5];
```

In summary, choose between `final` and `const` based on whether the variable's value needs to be determined at compile time. If so, use `const`; if the assignment relies on runtime computation, use `final`.

Dart: How to Declare Constants?