I dont think there is any difference in the type, Look at the Vickers Viscount, there were various marks for different airlines, ie, V757s for Air Canada V701s for BEA, but at the end of the day, they were V700 srs Viscounts.
Same applies to Boeing aircraft, B757 236 is the same as a B757 225, its simply a 757 200 srs.
I beleive this applies to Airbus aswell in most respects

Sorry but no. Boeing and Airbus use different numbering as described in the replies above.