波音航機編號後的 -X00 有什麼意思？

這是代表波音737的第8種型號, 波音737系列由1960年代面世至今已推出8款不同的型號. 737-800(行內人會稱之為738)就是737系列中比較新的型號.

正如本港各大航空公司中常見的747-400(744), A330-300(A333), A340-200(A342)等等.

It is the variations of the particular aircraft type.
The bigger the number does not necessary means its bigger.
B737-700 is smaller than B737-400. But the -700 is the new generation of B737 series family with glass cockpit.

It means the generation of size of the aircraft