So I am confused between all these four styles of declaring and defining a function ? all these work similarly but there must be a subtle difference between them :D

var sayHello = function() {
  console.log("hello")
  console.log(arugments)//works
  console.log(this)//works
}

function sayhello() {
  console.log("hello")
  console.log(arugments)//works
  console.log(this)//work
}

var SayHello = function f() {
  console.log("hello")
    console.log(arugments)//works
  console.log(this)//work
}

var SayHellO = () =>{  
   console.log(arugments)//doesnt works
  console.log(this)//works
}