Placeholder using html helper method in mvc

I have using without model class.

Type One:

First Method like as below type, it is using placeholder and null attribute type method
@Html.TextBox("firstname",null, new {placeholder = "enter your name"})


Type Two:


Second Method like as below type, it is using placeholder and without using null attribute type method

@Html.TextBox("firstname"," ", new {placeholder = "enter your name"})


Demo: