UK Parties vs US Parties

Major Parties

Both the UK and the US have two main political parties. In the UK, these are the Labour Party and the Conservative Party, whereas in the US, they are the Democratic Party and the Republican Party.
One key difference is that the US parties are ideologically more distinct, with the Democrats being more to the left and the Republicans more to the right on the political spectrum.

Party structure is more disciplined and unified in the UK, with members of the party often voting as a whole on parliamentary matters, whereas in the US, party members often vote independently and benched on their constituents’ interests or the particular issue at hand.
UK parties have a more centralised power structure with the party leader having a significant control over the party’s policies and direction. In the US, power is more dispersed within the party with the presidential candidate typically not having a defining control over the party’s platform.

The UK has a ‘first past the post’ electoral system which practically leads to a two-party system. The US, albeit having a two-party system, applies a different voting system—the Electoral College—for presidential elections which gives somewhat proportional representation to smaller states.
Third parties or independent candidates have an even more challenging time achieving significant representation in both systems. However, within the US, independent candidates may play greater roles in particular state or local elections.

UK party membership is subscription-based where members pay an annual fee and get a say in internal party matters such as leadership elections. In contrast, US parties do not have a formal concept of membership: anyone can declare themselves a member of a particular party.
Funding in both countries relies on donations and fundraising, but US parties have a greater reliance on private donations and, as such, money often plays a larger role in the US political system.

Policy formation in the UK is more party-driven, with the party influencing its members’ position on issues. In the US, individual politicians have more significant latitude to diverge from the party line.
Ideologically, US political parties have become more polarised in recent years, with less overlap between the two main parties. In contrast, UK parties, while showcasing clear ideological differences, exhibit a more moderate political spectrum regarding policy positions.