Hi guzz,
I think the current RCN has gone back to wearing the buttons that we wore prior to the 1968 debacle!
The pre '68 RCN buttons were basically identical for officers & ratings, but the CPO/PO buttons had horizontal lines running in the background, whereas the officers buttons were plain gilt with a rope surround.
I have shown a photo of the CPO/PO gilt buttons as that is all I have on file.
CPO/PO buttons
Officer buttons - don't have a close up photo but I think you will be able to view the differences in the officer's buttons compared to the CPO/PO buttons.
I expect there may be no difference in what they two grades are wearing now tho - I think they will be the same,
Best wishes!
Bryan