I agree that they look alike, but if you are just an avid bird watcher, you instinctively know what you need to be looking at right off the bat.
And to be honest, those differences to my eye are VERY noticeable. And I'm no scientist. Bird watching is strictly a hobby.
I'm not too upset about the environmentalists delaying another federally subsidized project for rice farmers, but I don't see how anyone can do much of an impact study on such an elusive creature.