The paint on OJB was getting tired, and like all RR 400s it went in to be redone (with the standard colours).
OEJ is an ER, and came delivered as the new Wunala. The only difference between it and the old, is that the GE engines retain their standard grey unlike the Red Rollers OJB had.
OJB is also no longer the "City of Sydney", but rather the "Mt Isa", presumably one of the ERs have been named such, or the A380s will be.
Lancer