With "difference training" I assume that any ICAO can provide the sign off? I fly most of the time a "simple" SEP, but have been known to fly complex high performance types in the UK. I don't have a JAR sign off for anything.
However I also fly / have flown Complex, high performance, glass aircraft along with MEP aeroplanes in the USA, for which I have the required sign offs / ratings.
I assume that these "sign offs" carry over in the same way as "ratings" carry over to G reg as well?