C++ Rvalue arrgument and move

Trying to understand the difference between rvalue formal parameter and call by value parameter.

When I called fun(move(Demo{}) I see only default constructor called once. While I called gun(move(Demo{}) I see default constructor and rval constructor called. Please some one help me to understand the behaviour of && formal argument type, uses of && in functions/member functions.

compilers clang++ , g++ , vc++

#include <iostream>
#include <utility>
#include <type_traits>

using namespace std;

class Demo {
    int i = 10;
public:
    Demo(){
        i = 40;
    }
    Demo(Demo && p) {
        i = p.i + 20;
        cout << "I am in Demo && " << endl;
    }
    Demo & operator = (Demo & p) {
        cout << "I am in operator && " << endl;
    }
    Demo & operator = (Demo && p) {
        i = p.i + 10;
        cout << "I am in operator && " << endl;
    }
    ~Demo(){
        cout << "I am in ~Demo " << i << endl;
    }
};

void fun(Demo & d) {
    cout << "fun( &) " << endl;
    cout << " -- End --  " << endl;
}

void fun(Demo && d) {
    cout << "fun( && ) " << endl;
    std::cout << std::boolalpha;
    cout << "Lvalur reference : " << is_lvalue_reference<decltype(d)>::value << endl;
    cout << "Rvalue Refernce  : " << is_rvalue_reference<decltype(d)>::value << endl;

    cout << " -- End --  " << endl;
}

void gun(Demo d) {
    cout << "gun( ) " << endl;
    std::cout << std::boolalpha;
    cout << "Lvalur reference : " << is_lvalue_reference<decltype(d)>::value << endl;
    cout << "Rvalue Refernce  : " << is_rvalue_reference<decltype(d)>::value << endl;
    cout << " -- End --  " << endl;
}
int main() {
    cout << "Main begin " << endl;
    fun(move(Demo{}));
    cout << "------------------- " << endl;
    gun(move(Demo{}));
    cout << "Main End " << endl;
}

//Output

Main begin
fun( && )
Lvalur reference : false
Rvalue Refernce  : true
 -- End --
I am in ~Demo 40
-------------------
I am in Demo &&
gun( )
Lvalur reference : false
Rvalue Refernce  : false
 -- End --
I am in ~Demo 60
I am in ~Demo 40
Main End