Sensational photos Shorty. One bird has a hook at the end of it's beak and the other doesn't. One bird is more scalloped on the back, rather like a female white-backed Magpie. At this time of year you would expect that they are both adults. Well done. 5 koala stamps.
Thanks @RobParnell. I would think with the buff tips the paler bird would be an immature. I don't think the time of Year would rule that out as they don't get full adult plumage until their third Year? Check my sighting 4586344 where I have photos of a juvenile in August.