First I made a mistake in my first post. What I meant was: FM part boards (hardware) and SOFTWARE can be different (from different suppliers). Yet it seems to me that there might be a combination of Thales hardware and Honeywell software, but that's just guessing.
Regarding the FMGC: The FG part of the units is to my knowledge always from Thales. So is the housing... The FMGC isn't like a Honeywell FMC. Infact it's like a Honeywell FMC together with a Collins FCC, like on the 757 for example.