Air commodore is never shortened to Commodore, which is a rank in various naval forces. Air commodore is a one-star rank and the most junior air officer rank, being immediately senior to group captain and immediately subordinate to air vice-marshal. It has a NATO ranking code of OF-6 and is equivalent to a commodore in the Royal Navy or a brigadier in the British Army or the Royal Marines. Unlike these two ranks, however, it has always been a substantive rank. Additionally, air commodores have always been considered to be air officers whilst Royal Navy commodores have not since the Napoleonic Wars
Rear admiral (Royal Navy) period included. The Royal Navy rank of rear admiral should be distinguished from the office of Rear-Admiral of the United Kingdom, which is an Admiralty position usually held by a senior (and possibly retired) "full" admiral. Rear admiral (Royal Navy) Rear admiral (RAdm) is a flag officer rank of the British Royal Navy. It is immediately superior to commodore and is subordinate to vice admiral. It is a two-star rank and has a NATO ranking code of OF-7. The rank originated in the days of naval sailing squadrons and each naval squadron would be assigned an admiral as its head.