Difference between Model and ModelAndView in Spring MVC :    

     @RequestMapping(value = "/testmap", method = RequestMethod.GET)
    	public ModelAndView testmap(ModelAndView model) {
    		ModelMap map=new ModelMap();
    	    String greetings = "Greetings, Spring MVC! testinggg";
    	    model.setViewName("welcome");
    	    map.addAttribute("message", greetings); 
    	    return model;
    	}
	
Why this code does not print the attribute message?