In c++, when accessing member variable in a class, any difference between using a.var and a.var() : Just for example

    Class A{
        public: 
        int a;    
    };

    int main(){
        A test;
        int b = test.a;
        int c = test.a();  
    }

My question is that when accessing the member variable of a class, is there any difference between using test.a and test.a()?