The biggest difference between compressed air and Refrigerated Liquefied Air is the oxidizing property of the later, IMDG Code lists both as :
UN 1002 AIR, COMPRESSED Class 2.2
UN 1003 AIR, REFRIGERATED LIQUID Class 2.2 with subsidiary risk 5.1 (oxidizing agent)
Observation for UN 1003 in the IMDG Code states “Liquefied, non-flammable gas.Strong oxidizing agent.Mixtures of liquid air with combustible materials or oils may explode. May ignite organic materials”.
IMDG Code Compliance Centre 