Regiment/Battalion
Armoured and Artillery Regiments
An Armoured Regiment is made up of
Usually contains between 450 and 650 soldiers.
Commanded by a Lieutenant Colonel, it has both administrative and tactical capabilities. Each Regiment has its own number and title, with distinctive designations that reflect its historical traditions. These distinctions include the regimental Battle Honours, Colours or Guidon, cap badge, cross belt plate, collar badge and buttons. Over time, these traditions help to build each Regiment's unique 'family' and 'spirit'.
(Taken from the British Army Website - Army Website)
As far as the rest of the world is concerned it's the same shape and size as a Battalion, does the same job as a Battalion and is marked on a map as a Battalion. Except for the Royal Tank Regiment, which consists of two regiments, and the Royal Regiment of artillery which consists of a couple of dozen regiments but does not incude the Honourable Artillery company, which is a battalion sized regiment called a company. Got all of that??
Just look on it as one of those traditions that confuses foreigners and you'll see that it's a good thing.
Infantry Regiments
An Infantry Regiment is made up of one or more battalions.
Army | Corps | Division | Brigade | Battalion/Regiment | Company/Squadron/Battery | Platoon/Troop | Section |