The single-aisle airliner market is one of the most lucrative and hotly contested segments in the aviation business. But for the past 15 years, that white-hot competition has almost exclusively been between two companies — Airbus and Boeing.

In recent years, companies from around the world have launched aircraft aimed at breaking the Airbus-Boeing duopoly.

On Wednesday, the latest challenger made its world debut in the form of the Irkut MC-21.

In addition to the Russian Irkut, there are a slew of state-of-the-art airplanes from around the world designed to challenge the Airbus A320neo family and the Boeing 737 MAX-Series.

But before we get to the challengers, lets take a look at the Airbus A320neo and the Boeing 737 MAX.