B-HLQ
I Agree
Airbus use the following nomencalture for the numbers after the -
1st number is series, e.g. -200
2nd is engine manufacturer, 0= GE,1= CFMi, 2=PW, 3= IAE, 4=RR, 5 = EA (maybe)
3rd is engine in series, e.g. Trent 768 was 1st option in Trent 700 family so is 1, Trent 772 is 2, Trent 772B is 3
I hope the last point answers the question for 747Focal, in that the GE engine in question is a later version on the -203.
FixA24
I Agree
Boeing use the 1st number as the series and the next two numbers or letters as the airline identifier that bought the aircraft originally from Boeing. I don't believe it changes as aircraft are sold to 2nd and subsequent operators.