Simplify the following text for a Grade 8 native English-speaking person.
Original: The Greater London Authority , London Assembly and the directly elected Mayor of London were created in 2000 by the Greater London Authority Act 1999 .
Simplified: In order to avoid confusion , Greater London is often used to distinguish the whole modern urban area centred on the City of London from the City of London itself . When most people say London , they are referring to Greater London .