Format

// Function Expression
const expression = function () {
    console.log('this is a function expression);
}

// Function Declaration
function declaration () {
    console.log('this is a function declaration);
}

Difference

1. Name

   • A function expression is a function assigned to a variable (which has a name). So the function itself can be anonymous.

   • However, a function declaration must include a name.

2. Hoisting

   • Hoisting is allowed only in the function declaration.

       expression(); // error
       declaration(); // this is a function declaration
     
       const expression = function () {
           console.log('this is a function expression');
       }
     
       function declaration () {
           console.log('this is a function declaration');
       }