Water Tender Ladders or WTL's as they are known are the general purpose type fire engines most commonly seen on the roads in the UK and which carry water for fire fighting as well as anscilliary equipment.
Rapid Intervention Vehicles or RIV's as they are known are the latest first responder vehicles that can get through traffic and into more restricted traffic areas to provide that all important first attack.
Emergency Water Tankers are what the fire service will call out when there is a major fire and where that fire is at a location where water is in very short supply or totally unavailable e.g. remote moorland fires
Aerials consists of aerial ladder / platform units (ALPs) and the newer combination appliances which have both extending ladder and platform as well as a WtL spec pumping delivery system.
Airport fire engines are a special type of appliance which in general are very big due to the need to carry up to 12,000L+ of water at speed and have monitors to throw foam considerable distances.
There are a variety of specialist vehicles that are used within the British Fire Service including the Hagglunds BV206 ATV which can carry equipment and personnel over rough terrain.