Just what are 'decorations' in this context? Gallantry medals and things such as MBE's?
The MBE comes in the category of "Orders", ie everything from the Most Noble Order of the Garter to the The Most Excellent Order of the British Empire. Precedence among orders is basically in chronological order of the founding of the order (lots of "orders" in that sentence, but you get what I mean!).
"Decorations" are what we would understand as gallantry awards, such as the DFC, AFC etc.