I have seen some interesting comparisons in regards to the two airports being built in Istanbul and Beijing, both of whom started in 2014 and will become major airports in the world.
They are similar in size, although the one in Istanbul is bigger in terms of area occupied as well as indoor space.
But, although larger in size, in terms of passenger capacity and the number of runways, Beijing Daxing Airport and Istanbul (Ataturk?) Airports are similar.
Passenger capacity: Beijing, 100 million; Istanbul, 90-120 million.
Number of runways: Beijing, 8; Istanbul, 6.
The reason must be the difference in the size of closed area. The one in Istanbul is bigger. So, probably they planned larger area for resting and shopping.
The most significant difference, however, is the cost: Beijing Daxing will cost, when complete, about 12-13 billion USD. Istanbul airport will cost about 34-36 billion USD (28 billion Euro).
The difference in costs cannot be explained by the difference in size. Could be due to the materials used, whether they are imported or locally sourced, and the labor cost.
But, I have seen images of laborers protesting in the Istanbul airport due to unpaid salaries, so, one wonders where does the truck loads of USD goes into.
Nonetheless, both are immense projects and about to be complete. Beijing airport's metro is ready to run, not sure about Istanbul airport.
Istanbul new airport
Beijing new airport
https://en.wikipedia.org/wiki/Istanbul_New_Airport
https://en.wikipedia.org/wiki/Beijing_Daxing_International_Airport
In numbers | Istanbul's new airport
Capacity : 150 million passengers with the potential for that to be increased to 200 million
Countries within three hours : 120
Square metres : 76.5 million
Hotel rooms : 451
Passport control desks : 228
Waiting seats : 20000
Terminals : 2
Runways : 6
Parking spaces : 40000
Top 20 | The world's busiest airports
Ranking Airport Passengers in 2017 % change
1 Atlanta 103.9m -0.3
2
Beijing 95.8m 1.5
3 Dubai 88.2m 5.5
4 Tokyo Haneda 85.4m 6.5
5 Los Angeles 84.6m 4.5
6 Chicago O'Hare 79.8m 2.4
7 London Heathrow 78m 3
8 Hong Kong 72.7m 3.4
9 Shanghai 70m 6.1
10 Paris Charles de Gaulle 69.5m 5.4
11 Amsterdam 68.5m 7.7
12 Dallas/Fort Worth 67.1m 2.3
13 Guangzhou 65.9m 10.3
14 Frankfurt 64.5m 6.1
15
Istanbul 63.9m 6
16 New Delhi 63.5m 14.1
17 Jakarta 63m 8.3
18 Singapore Changi 62.2m 6
19 Seoul Inchoen 62.2m 7.5
20 Denver 61.4m 5.3
there are also Sabiha Gokcen Airport in Istanbul
so ATATURK Airport 63.9 million + Sabiha Gokcen Airport 31.3 million = total of 95,2 million by 2017
The construction will be carried out in four phases, and the first is scheduled to open on 29 October 2018
and be fully operational by 2028
The new airport will have six runways and flights to 350 destinations and an eventual annual capacity of 200 million passengers
and will also feature a 451-room hotel
The world's biggest duty free shop
Istanbul's new airport expected to be global aviation hub
and Istanbul New Airport will facilitate Turkish Airlines’ growth plans
Turkish Airlines flies to more countries in the world than any other airline
and Turkish Airlines buys 255 new Planes for $40 billion between 2018 and 2023
-- 92 Airbus A321Neo $11,6 billion ( 2018-2022 )
-- 98 Boeing 737 Max $10 billion ( 2018-2021 )
-- 40 Boeing 787-900 Dreamliner $11 billion ( 2019-2023 )
-- 25 Airbus A350-900 $7,7 billion ( until 2023 )
also 8 Boeing 747-8İ Super Jumbo Jet $3 billion ( planed )
and Turkish Airlines bought 135 planes for $23 billion between 2013 and 2017
-- 34 Airbus A321-200 $3,9 billion .... ( 2013-2017 )
-- 36 Boeing 737-800 $3,5 billion .... ( 2013 - 2016 )
-- 15 Boeing 737-900ER $1,5 billion ... ( 2013 - 2015 )
-- 27 Airbus A330-300 $7 billion ( 2013-2017 )
-- 23 Boeing 777-300ER $7,3 billion ( 2013-2017