difference between expression and declaration 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: js function expression

const plantNeedsWater = function(day){
  if (day === 'Wednesday'){
    return true;
  } else{
    return false;
  }
}

console.log(plantNeedsWater('Tuesday'))