What is the difference between the British Parliament and the US Congress?

In the
British Parliament, the party that governs is, by convention, the one that can command majority
support in the House of Commons. Once that majority is secured, the government is entitled to
propose whatever legislation it wishes. In the United Kingdom, Parliament is sovereign and there
exists no other institution with the power to strike down legislation in the same way as the US
Supreme Court. The British constitution is unwritten, and so there is no mechanism by which
judicial review may be used to void Acts of Parliament. English courts can certainly rule
government actions unlawful, but it cannot strike down legislation.

Both
houses of Congress are wholly elected. In the United Kingdom, however, this only applies to the
lower house, the House of Commons. The unelected House of Lordsthe upper chamber in the UK
Parliamentcan certainly delay legislation and inflict defeats on the government of the day.
However, if needs be, the government can always enforce the Parliament...