English Government vs American Government

[Aidan Phoenix]

Over the last year or so I've been researching different aspects of English government in order to find their equivalent to certain branches of American government agencies. You see, when I write I like to be as accurate as possible and will try my best to Google the information I need. So far I've been lucky in finding what I need.
For example, last year I wanted to know what Britain called their Immigration and Naturalisation Services. If I'm not mistaken, it's the Border Agency. Tonight I sought the title of their version of the Occupational Safety and Health Administration (OSHA) and found the Health and Safety Executive.
What other government branches and agencies do England and America both have, but are named differently?