Final answer:
The IATA format uses three-letter codes, while the ICAO format uses four-letter codes to identify airports.
Step-by-step explanation:
The International Air Transport Association (IATA) and the International Civil Aviation Organization (ICAO) have different formats to identify airports.
The IATA format consists of a three-letter code that represents airports. These codes are primarily used in airline reservation systems, baggage handling, and ticketing. For example, 'LHR' represents London Heathrow Airport.
The ICAO format, on the other hand, consists of a four-letter code that represents airports. These codes are used by pilots, air traffic controllers, and aviation authorities for communication purposes. For example, 'EGLL' represents London Heathrow Airport in the ICAO format.