British Aerospace (Hawker-Siddeley/Avro) 748
In the 1960s many manufacturers were looking to finally replace the Douglas DC-3, and the aircraft that were meant as replacement, like the Convair 340. Avro designed model 748, a fifty seat Rolls Royce Dart powered turboprop aircraft. Soon after, the company merged with Hawker-Siddeley and the aircraft became known as the HS748. The final manufacturer to built the aircraft was British Aerospace, as the BAe748.
Like the contemporary Fokker F27 it has large oval cabin windows. The rounded nacelles are typically suited for the Dart engines and also leave room for the main gear. The nose is quite round, with as finishing touch narrow eyebrow cockpit windows. Finally the tail has a forward swept trailing edge and a big dorsal fin.
How to recognise the different versions of the HS748 will be added later.
Confusion possible with
Of course you are most likely to mix-up the British Aerospace 748 and ATP, as the ATP was derived from the 748. The ATP is longer, has a more pointed nose, more and rectangular cabin windows, different nacelles, six blade props and a swept trailing edge of the vertical stabiliser.
The YS-11 is larger than the 748 and has many small rectangular cabin windows, but otherwise looks just like the 748.
Although a bit smaller the Gulfstream I has many similar elements as the 748, especially the engine nacelles. However, you can easily keep them apart by the fewer but much larger oval cabin windows of the Gulf.
Given the same basic configuration the Convairliners could be mixed up with the 748, but this is less likely given the rectangular cabin windows, more curved leading edge of the vertical stabiliser and dorsal fin, different nacelles and upward opening cabin door of the Convair 240, 340, 440, 580 and 600/640.