If there is no difference between the two, why is everyone fighting so much?
It makes no sense.
Sure it makes sense. You follow sports? Have a "favorite" team? Doesn't your team have exactly the same number of players as the other team, filling the same positions and trying to win for the team? But you still have one team you favor over another.
That's politics today. People have a "team" they support. And fighting for the team you support and against the team you want to lose is AMERICAN at its core.
It's all about winning and losing and rooting for your team. Doesn't really matter if YOUR team is basically like the other guys team. You just wanna support YOUR team.