differnce between function declaration and function expression? code example

Example 1: function expression vs function declaration

const functionExpression = function(width, height) {
  return width * height;
};

console.log(functionExpression(3, 4));
// Result = 12

function functionDeclaration(width,height){
return width * height;
};

console.log(functionDeclaration(3,4));
//Result = 12

Example 2: function expression

const getRectArea = function(width, height) {
  return width * height;
};

console.log(getRectArea(3, 4));
// expected output: 12