What exactly is the difference between an NGO and a political party? They’re both volunteer-based groups formed to promote certain political viewpoints in public government. Both are primarily funded by donation or personal wealth and achieve their goals through support of ideologically similar candidates and targeted demographic advertising.

Possible Distinctions I Discarded

Non-For-Profit

Political organizations are tax-exempt.

And really, would any but the most Objectivist of parties tell you they are for profit?

Ability to Run Political Candidates

The Nation of Islam ran Abdul Alim Muhammad, Shawn Brakeen, and George X Cure for various state government positions in 1990.

Capacity to Operate Transnationally

The Arab Socialist Ba’ath Party is active in multiple Middle Eastern countries.

Independent of Government Influence

And parties aren’t?