Given a choice, I'd be willing to exchange Labor Day for Ronald Reagan's birthday, but Satan will be ice skating in Hades before that happens.
Yes, there is a difference. A Federal holiday closes all Federal offices, only. A national holiday closes all government offices (such as states) and banks. A national holiday is more likely to be observed by a private company. For example, at my company, I get MLK day off, but I don't get Columbus day.