A parliamentary form of government, such as in the UK, is similar to the US Congress in the sense that it's based on the idea of having elected or appointed representatives who pass laws and perform checks and balances in government. As the most powerful legislative branch of the government, this body of lawmakers has a bicameral structure in both the US and the UK.
While Congress is divided into the upper Senate and the lower House of Representatives, the UK Parliament consists of the upper House of Lords and the lower House of Commons.
The main similarities of the two political systems are in the lower house, as the House of Lords contrasts with the Senate in various ways. As an example, lower house members are elected by the public, whereas House of Lords officials are appointed.
The leader in both lower houses, elected by fellow members, is called "Speaker of the House." Members can be expelled from government in each system.
Bills can be introduced in either house. Usually after a bill is approved in one house, it is sent to the other for a confirmation vote following a debate of the issue. In the US, if the bill passes in both houses, it is sent to the president for approval. However, in the UK, a bill becomes a law after it is approved by both houses then receives "Royal Assent" as an Act of Parliament.
Both systems have two major parties that dominate politics, mixed with smaller independent parties. In the UK the Conservative Party is similar to Republicans, reflecting the interests of free-market business executives, while the Labour Party parallels the worker ideologies of Democrats.