Inheriting from public vs private class C++

Question

So let's say I've got 2 classes like this :

Shape

class Shape
{
private:
    //private members

public:
    //public members
};

Triangle

class Triangle : Shape
{
private:
    //private members
public:
    //public members
};

What is the difference between class Triangle : public Shape and class Triangle : Shape if there's any ?