Airbus A320 family

Apart from more subtle differences the A320 family has - compared to the 737 family - a less pointed nose, different cockpit windows without the typical V shape, a smaller dorsal fin, fully enclosing main landing gear doors and smaller nose landing gear doors when the gear is extended.

Dassault Mercure

The 737 can best be distinguished from the Dassault Mercure by its engines nacelles and cockpit windows. The Mercure has long nacelles with a conical plug in the exhaust. The last cockpit window has a triangle shape; there is just one eyebrow window.

Airbus A220

Formerly known as the Bombardier CSeries the Airbus A220 has the same basic configuration as the Boeing 737. The A220 has four cockpit windows, a flat tail cone, oval cabin windows and canted winglets as main recognition points.

Comac C919

This Chinese jetliner has a larger resem­blance with the A320 than the Boeinng 737, considering the four cock­pit windows, short nose gear doors and bent-up wing tips on the C919. (photo: Ken Chen/WikiMedia)

The Boeing 737-300 is the first of the second generation, now called 'classic' family, with the 737-100/200 being the 'orginal' series. The difference compared to the original 737s is easy: the engine nacelles are shorter, and have a larger diameter and separate fan exhaust. Quite characteristic is the flattened bottom of the nacelle. Moreover, the vertical stabiliser now has a triangular dorsal fin.

Originally, 737-300s were delivered without winglets. They can however be equipped afterwards with tall blended winglets from the wingtip up. Sometimes these are referred to as 737-300SP.

Several companies offer cargo conversions of 737-300, after which they are known as 737-300F or 737-300BDSF, depending on the company that performed the conversion, Pemco or IAI Bedek. In both cases a large cargo door is installed in the left front fuselage and cabin windows are replaced by metal plugs.

The Quick Change (QC) version of the 737-300 has a large cargo door, but retains the cabin windows.

The Boeing 737-400 is the longest of 'classic' family, with a fuselage stretched about 3.5 m compared to the 737-300. To accommodate the larger number of passengers, the number of overwing exits is two on each side compared to one for the 737-300 and -500.  For the rest the 737-400 is the externally the same as the 737-300, except that they cannot have winglets.

This is the cargo version of the Boeing 737-400, converted from passenger aircraft. The cabin windows have been replaced by metal plugs. The 737-400SF is still recognisable by the two overwing emergency exits on each side.

After the 737-400 Boeing developed the shorter 737-500, as a more direct replacement for the original 737-200. It has about the same dimensions as that aircraft, but of course has the characteristics of a 'classic' 737. Like the 737-300 it has one overwing exit on each side. It is only the length that helps you identify a -500, so count the cabin windows if you are in doubt. Like the 300 series the 737-500s can be equiped with blended winglets, after which they may be called 737-500SP.

The 737-600 is the smallest of the 'Next Generation' (NG) family, the third generationof the Boeing 737. It is comparable to the 737-500 in length, but has the properties of the rest of the NG series. What is most apparant is the larger vertical stabiliser of the NG, on the -600 in particular. Further­more the NG series have an increased wing span compared to the Classic 737s. This concerns the part outside the trailing edge flaps. You can see it well when you see a Classic and a Next Gene­ration from the front, side-by-side. Compare the detail photos of the 737-300 above and the Next Gene­­ration one below and you will see what we mean. Other differences with regard to the second generation are the slightly less flattened engine cowlings.

No 737-600s have been fitted with winglets, unlike longer members of the Next Generation 737s.

The first 'Next Generation' (NG) family was the 737-700. It is comparable to the 737-300 in length, but has the properties of the rest of the NG series: a larger vertical stabiliser, an increased wing span and the slightly less flattened engine cowlings. Because of the relative dimensions of the vertical tail compared to the fuselage length, the 737-700 is most often confused with the 737-500.
Most 737-700s have been fitted with blended winglets, but there are still a few without winglets.

To compete with the Gulfstream and Bombardier large cabin jets Boeing mated the fuselage of the 737-700 and the (heavier) wings and landing gear of the 737-800 to create the Boeing Business Jet (BBJ). Externally it is not different from the standard 737-700. After the introduction of the corporate version of the 737-800 the original BBJ became known as BBJ1.

The US Air Force operates the BBJ as the C-40B and C-40C. The main difference between the B and the C model is the communication systems, which are more advanced for the C-40B to allow it to be used as an "office in the sky" for senior military and government leaders. The C-40C is more a basic passenger transport aircraft.

ANA All Nippon Airways was the launch customer for the 737-700ER, where ER stands for Extended Range. Just as the BBJ is has the wings and undercarriage of the 737-800, to allow a higher maximum take-off weight to carry the extra fuel for the longer range. It is externally the same as the standard 737-700.

The 737-700C is a version with a large cargo door on the left side. This is what differentiates this version from other 737-700s. It still has many cabin windows. Most 700Cs have been delivered as C-40A Clipper of the US Navy.

The Boeing 737-700C convertible is quite a rare aircraft, as only a handfull commercial versions have been delivered. (photo: Eric Salard/WikiMedia)

The most popular NG version is the 737-800, built as successor of the 737-400. So it has about the same length as the -400 but a larger vertical stabiliser, wider wingspan and more rounded engine nacelles. Compared to the 737-600 and -700 it has two overwing exits on both sides. Nearly all 737-800 have been fitted with winglets, the blended winglets and split-scimitar winglets.

The BBJ2 is the corporate jetliner version of the 737-800. It is not recognisable from the standard model.

Boeing has developed a freighter conversion of the -800. It has a large cargo door in the left side, forward of the wings. The cabin windows have been replaced by metal plugs. The marketing name depends on the holding of the supplemental type certificate, Boeing (BCF-Boeing Converted Freighter), IAI Bedek (BDSF, Bedek Special Freighter) or AEI (SF, for Special Freighter).

Three companies offeer a cargo conversion of the Boeing 737-800. This 737-800BCF is an 'official' Boeing version of the 800 series freighter. (photo: Windmemories/WikiMedia) 

The Boeing 737-900 is the longest version of the Next Generation family. Compared to the -800 the fuselage is about 3 m longer. It is quite difficult to distinguish from the -800, because the standard -900 has the same door configuration (two main doors and two overwing emergency exits on each side), unlike the -900ER.

To accommodate a higher number of passen­gers and still comply with regulations for eva­cua­tion the 737-900ER has a third emergency exit on each side, aft of the wing. Its size is in between the overwing exits and the main cabin doors. For the rest the aircraft is the same as the basic 737-900.

The BBJ3 is the corporate jetliner version of the 737-900ER. It is not recognisable from the standard model.

The smallest member of the fourth generation Boeing 737, the MAX series, is the MAX7, desig­nated 737-7. It is slightly longer than the 737-700, but still significantly shorter than the next member of the family, the MAX8. Still, it has two overwing emergency exits. Therefore the length is the way to recognise the MAX7 from the larger MAX version. For the rest look at the characteristics of the MAX series: nearly round engine nacelles (compared to flattened at the bottom) with serrated fan exhausts, a longer tail cone and revised advanced technology winglets. The winglets are similar to the split-scimitar winglets available on the Next Generation aircraft, but have a but different shape.

The 737 MAX8 has the same length as the 737-800, so it is much longer than the 737 MAX7. It differs from the 800 series by the engine nacelles, tailcone and winglets (see description at 737 MAX7 for details about the characteristics of the MAX series). The standad 737-8 has two small emergency exits above the wings, like the 737-7.

Especially for Ryanair Boeing created a high density vesion of the MAX8, marketed as MAX8-200 (or MAX200), because it can seat up to 200 passenger. It has the same length as the MAX8 and extra (large) emergency exit behind the wing: the standard MAX8 does not have this.

Being the replacement for the 737-900 the 737 MAX9 has (nearly) the same length as its predecessor. The MAX characteristics (see description at 737 MAX7) make it easy to recognise from the 900 and 900ER. Still it may be difficult to distinguish the MAX9 from the MAX8-200 and larger MAX10 because all models have an extra emergency behind the wing and the only apparent difference is the fuselage length.

Boeing developed an airborne early warning & control version based on the 737-700ER frame, which can be recognised by the large bar on top of the fuselage. As this significantly disturbs the airflow, it has two ventral fins.

It was first delivered to Australia, where it was nicknamed "Wedgetail". This name stayed even for other customers; the Royal Air Force calls it Wedgetail AEW1. It is officially designated E-7 or E-7A though.

Boeing builds a maritime surveillance aircraft that is based on the 737-800. The main differences compared to the standard -800 are the raked wingtips and the lack of cabin windows, and of course the mission equipment. The US Navy designates the aircraft as P-8A Poseidon, Boeing as 737-800A. In UK military service the aircraft is known as Poseidon MRA1.