In the Flutter framework, final and const are both used to declare variables that cannot be changed after they are initialized. However, they differ in how they are implemented and when they are evaluated.

final variables are evaluated at runtime, meaning that their value is not determined until the program is running. This allows final variables to be different for each instance of a class or object.

const variables, on the other hand, are evaluated at compile-time, meaning that their value is determined when the code is compiled. Because const variables are evaluated at compile-time, they must be made up of compile-time constants, such as literals, null, or references to other const variables.

Here’s an example of how you might use final and const in Flutter:

class MyWidget extends StatefulWidget {
  final int someValue;
  const MyWidget({Key key, this.someValue}) : super(key: key);

  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  static const double _someConstant = 3.14;

  @override
  Widget build(BuildContext context) {
    return Container(
      width: widget.someValue * _someConstant,
      height: widget.someValue * _someConstant,
    );
  }
}

In this example, the someValue field is declared as final, meaning that it can be set when the MyWidget object is created, but it cannot be changed after that. The _someConstant field is declared as static const, meaning that it is a compile-time constant that is shared by all instances of the _MyWidgetState class.