Question : Whats the difference? $var and $_var

Check these 2 classes,

class Class1
{
    private $_name;  
    private $_job;  
    private $_age;  
}


class Class2
{
    private $name;  
    private $job;  
    private $age;  
}

Is there any difference using a '_' before the variable ?

Answer : Whats the difference? $var and $_var

It makes it  different variable.