The Green badge is the second highest level of guiding qualification and shows that a person is qualified to guide in one particular city. The Blue Badge is the highest level of guiding qualification which covers several counties.
A Green Badge Guide may hold a badge for more than one city, and a Blue Badge Guide may hold a badge for more than one region. The badge will state where the qualification is held for, for example the one shown is for the Heart of England region which covers Gloucestershire, Herefordshire, Oxfordshire, Shropshire, Staffordshire, Warwickshire, West Midlands and Worcestershire.
In addition to the badges, guides can train to receive an endorsement, which is for a particular building or place. I have the 2012 Venues endorsement which covers the places used for the London Olympic games.