What are the difference of MD Request/Response used in Foreign Exchange for FIX4.2 and FIX4.4?

Imported from previous forum

Hi,

I am planning to use market data request/response in Foreign Exchange, like simple Spot or Outright. May I know what the differences of market data request/response in FIX 4.2 and 4.4 will have impact on FX implementation?
Thanks.

Janice