It could be that William Lockie made smaller sizes for the Far East, but it also does private label work, so it could just be that Japanese brands ordered smaller sizes.
The way knits are measured is the same. If you are slim like me, then a 40 would fit you better. WL sizes their knits by chest size of the knits, not the chest size of the wearer. So someone whose size is 38 would wear a sweater in size 40 or 42, depending on the fit desired.