Oh look, they agree on some issues, surely we are voting for the same thing now. Let's ignore their implementation difference, also ignore their disagreements on other issues, I tell you they are the same because only if they disagree on every single issue, then they can be called different.
It's a competition to decide on who may use the power of the state (force and coercion), at the expense of the people, to advance their ideology and make richer their donators.