C++11 - What is the difference between CTOR() = default and empty CTOR(){}? [duplicate]

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• The new keyword =default in C++11 3 answers

C++11 introduced new keyword default to force creation of default constructor:

class MyClass {
    MyClass() = default; // <==
    MyClass(int num);
};

I could not find the reason to use it over empty constructor.

class MyClass {
    MyClass() {} // <==
    MyClass(int num);
};

Could anybody enlighten me?