For Airbus: the three numbers, in e.g. the -211 in A320-211 have the following meaning:
-first number is the sub-model of the aircraft: in the above example an A320-200
-second number is the engine manufacturer: 0 is GE
, 1 is CFM, 2 is P&W, 3 is IAE, 4 is RR
. I believe 5 will be the Engine Alliance (A380)
-third number indicates the versions of the model, after minor technical changes, or newer engine versions, higher MTOW, etc...