Aircraft model & series number.

Aircraft model number designates, the family to which it belongs.e.g. Narrow body 737 Or Wide body 777.

Series number indicates speciality of that particular aircraft. If you want to know the detail about any particular model like,  flying range , size ,capacity then you should focus on its series number .Some airlines modify their aircraft as per their operational experience and it is called 'retrofitting'.

Retrofitting includes(but not limited) activity like reshaping fuselage size, fitting diffrent engines of same thrust rating or modifying cabin layout.'Retrofited' aircraft again  have a unique series number like B747 300 SP (Special performance). This B747SP was made for (short range minimum fuel and maximum passenger capacity). 

Fig 1 :B747SP(Special perfomance)B747 is a family and it has hundreds of sub-models, retrofitted. While writing,e.g. B737-800NG,  we can use very intelligent method which saves our time and space.It is written as 'B738'.

In app like flight radar, to save space, you will see model number is written as B748 instead of B747-8, B773 (B777-300ER), B738 (B737-800NG).

If there is 'a word' or 'a group or words'  attached to this model &series number then it gives more specific information about the aircraft.e.g. B747-300D.'D'  means 'Domestic'. This series was specially designed for Japan's domestic use.

More aircraft with special category:

1.In B777-200LR (Long Range): have belly fuel tank(extra fuel tank) because of which it can fly intrtglobe upto 14000km nonstop.

Fig 2 : Boeing 777-200 LR (Long range)2.B737 BCF ( Boeing converted Freighter) for Cargo operation. Similar version SF (Special freighter ) is also available.

3.Boeing 747-300 Combi: has half deck for passanger and half for carrying extra cargo.

4. B747- SUD (streched upper deck)5.B747 EFR: extended range freighter .6.B747 SR: Short range (Fuel tank minimum and pax load maximum)