To answer this question, you will read two articles. First, read Article 1. Planning for the construction of O'Hare International Airport began in 1945 when a committee chose Orchard Field as the location of the future airport. In 1955, the airport opened to commercial air traffic and O'Hare International Airport served as a hub for travelers throughout the world.

To respond to the increasing number of passengers, the airport expanded. O'Hare added a fifth runway and opened a terminal for international travel. Passengers could take flights to other countries and throughout the United States. The amount of land used by the airport grew to about 7,200 acres. This expansion included airplane hangars, cargo buildings, and even a post office. Next, there was an expressway built to connect O'Hare International Airport with downtown Chicago. People could travel to and from the airport quickly and easily, making it a desirable location. Finally, the main terminal building and parking lot were completed. These expansions led to a greater number of passengers. In 1962, 10 million passengers traveled through the airport that year alone. O'Hare was officially the world's busiest airport.

O'Hare's growth was accompanied by innovation. In order to increase efficiency, the airport developed a task force that allowed three runways to be used at the same time in 1976. The Passenger Facility Charge, which charged passengers for using the airport, was introduced in 1990. This money was used to improve and modernize the airport. The Airport Transit System was created to help transport passengers between terminals in 1993. In 1996, the O'Hare Noise Compatibility Commission was created to help surrounding neighborhoods deal with aircraft noise. To aid with the O'Hare Modernization Program, a Sustainable Design Manual was created in 2003. This cutting-edge document helped the airport think about the environment during the modernization process. The principles outlined in the manual were later used in a similar document in August 2009 that promoted environmental sustainability at the airport. Over the years, O'Hare International Airport has grown and innovated to manage its expansion.

Read Article 2 and answer the question.

Between O'Hare and Midway International Airports, over one thousand flights depart Chicago every day. When planes take off and land, they create vibrations. These vibrations create noise in Chicago neighborhoods. In the early days of both airports, the city of Chicago realized that aircraft noise was a problem. People were unable to talk on their phones, watch television, or sleep peacefully at night.

In 1996, the O'Hare and Midway Noise Compatibility Commissions were created to help solve the noise problem. The Commissions searched for ways to reduce the effect of aircraft noise on the surrounding neighborhoods. First, pilots and air controllers volunteered to follow the Fly Quiet Program. The program suggested that pilots use runways and flight paths over forests, highways, and industrial areas at night. By avoiding housing areas, pilots and air controllers decreased the noise level of the airplanes in these areas. That way, people would be able to sleep.

Next, the commissions focused on using sound insulation in homes near the airports. If residents lived in an area that experienced a high volume of noise, then they were eligible to have their homes insulated. Residents were given different options. Their homes could be insulated by installing special windows, doors, or air conditioning. Similar steps were also taken to insulate private and public schools in the affected areas.

The continued presence of the O'Hare and Midway Noise Compatibility Commissions is evident today. An Airport Noise Management System uses noise monitors to measure the noise levels in neighborhoods each day. A Community Outreach Vehicle distributes information about aircraft noise. Residents can use the Flight Tracker program. This online program shows images of where planes fly. If there is still a problem with noise, people can call the hotline or complete an online form.

How is the structure of Article 1 different from the structure of Article 2?