Différence entre déclarations d'objet

#ifndef _TEST_H
#define _TEST_H

class Test {
  int _a;
  int _b;

 public:
  Test(int a = 0, int b = 0);
  ~Test();
  inline int a() const { return _a; };
  inline void a(const int & a) { _a = a; };
  inline int b() const { return _b; };
  inline void b(const int & b) { _b = b; };
  void test (const Test & t);
};

#endif /* _TEST_H */

int
main(int argc, char ** argv) {
  Test * t1 = new Test(2, 2);
  Test * t2 = new Test();
  Test t3(32,41);
  
  std::cout << "t1 : a = " << t1->a() << " et b = " << t1->b() << std::endl;
  std::cout << "t2 : a = " << t2->a() << " et b = " << t2->b() << std::endl;
  std::cout << "t3 : a = " << t3.a() << " et b = " << t3.b() << "\n" << std::endl;
 
  t2->a(3); t2->b(4);

  std::cout << "t1 : a = " << t1->a() << " et b = " << t1->b() << std::endl;
  std::cout << "t2 : a = " << t2->a() << " et b = " << t2->b() << std::endl;
  std::cout << "t3 : a = " << t3.a() << " et b = " << t3.b() << "\n" << std::endl;

  t2->test(*t1);

  std::cout << "t1 : a = " << t1->a() << " et b = " << t1->b() << std::endl;
  std::cout << "t2 : a = " << t2->a() << " et b = " << t2->b() << std::endl;
  std::cout << "t3 : a = " << t3.a() << " et b = " << t3.b() << "\n" << std::endl;

  return EXIT_SUCCESS;
}

std::vector<Test *> _vecTest;