How to pass data to reference wrapper

Consider following piece of code:

//option no 1
struct foo{
    foo(baz &b) : _b(b){}

    std::reference_wrapper<baz> _b;
};

//option no 2
struct bar{
    bar(std::reference_wrapper<baz> b) : _b(b){}

    std::reference_wrapper<baz> _b;
};

I am wondering if there are any practical differences between initializing foo and bar. If so, what are the pros and cons of each solution and which should be prefered?