Commander (Cdr) is a senior officer rank of the Royal Navy of the United Kingdom. It is immediately junior to captain and immediately senior to the rank of lieutenant commander. Officers holding the junior rank of lieutenant commander are not considered to be commanders.
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Captain (Capt.) is a senior officer rank of the Royal Navy. It ranks above commander and below commodore and has a NATO ranking code of OF-5. The rank is equivalent to a colonel in the British Army and Royal Marines, and to a group captain in the Royal Air Force. There are similarly named equivalent ranks in the navies of many other countries.
Lieutenant colonel (Lt Col) is a rank in the British Army and Royal Marines which is also used in many other Commonwealth countries. The rank is superior to major, and subordinate to colonel. The comparable Royal Navy rank is commander, and the comparable rank in the Royal Air Force and many other Commonwealth air forces is wing commander.
The rank insignia in the British Army and Royal Marines, as well as many Commonwealth countries, is a crown above a four-pointed "Bath" star, also colloquially referred to as a "pip". The crown has varied in the past with different monarchs; the current one being the Tudor Crown. Most other Commonwealth countries use the same insignia, or with the state emblem replacing the crown.
Lieutenant commander (often abbreviated Lt Cdr), formerly more commonly lieutenant-commander, is a senior officer rank in the Royal Navy of the United Kingdom. It is immediately junior to commander and immediately senior to the naval rank of lieutenant.
The equivalent rank in the British Army and Royal Marines is major; and in the Royal Air Force, it is squadron leader.