I'm not sure if its ever been stated directly. I don't think many of the variants in TRO: Prototypes have gotten their own record sheets yet.
The description in the Technical Readout states that the 1A2 swaps the sword and Angel ECM (found in the 1A1) for a small vibroblade and TAG. Unfortunately, the weights don't match up (3.5 tons of gear removed, 4 tons of gear added).
So either 1A2 needs to lose 0.5 tons of armor, or it needs to swap its FerroFibrous for Heavy Ferro Fibrous. I'm not really sure which happens, as I don't think I've seen a record sheet for the 1A2.