Alot of people have trouble with this kind of stuff so I'll try to explain it.


The Army
An army is considered as every man you have from the lowliest private to your best General. But the term "army" usually means your troops in the field. "Armies usually consist of at least 100,000 men comprising of three corps of troops and their support units. Multiple armies working in tandem are classified as an "army group". Usually commanded by a 4-star General.

Corps
A corp is made up of 2-3 divisions and is usually comprised of 35,000-60,000 men. Variation in numbers is based upon what the corp is composed of. Infantry will have more manpower, and Armor will be counted by the amount of tanks. Usually commanded by a Lieutenant General (3-Stars)

Divisions
A Division is comprised of 2-3 brigades consisting of 8,000-16,000 men. In large-scale combat, this is what is usually fielded. Usually commanded by a Major General (2-stars)

Brigade
A brigade consists of 4,000-6,000 men made up of 2-3 regiments. As you probably guessed, a brigade is commanded by a Brigadier General.

Regiment
A regiment is standardized at approximately 1,500 men made up of 2-3 battalions. Usually commanded by a Colonel.

Battalion
A Battalion consists of 500-600 men and is comprised of 4-6 companies. One of the companies would be called Headquarters Company and has the job you would expect. Usually commanded by a Major.

Company
A company is between 100-120 men broken up into 3-4 platoons. Once again you have a Headquarters Group in addition to a Heavy Weapons platoon. Usually commanded by a Captain.

Platoon
The platoon is 30-40 men depending on their composition split into 4 squads. Again, there is Headquarters, and Heavy Weapons. This is the largest unit that has a officer attached, commanded by a 1st or 2nd Lieutenant.

Squad
The squad is the smallest organized unit an army has. It is composed of 8-12 men, and is usually led by a Sergeant. It is rare to have more troops assigned than numbered but it is not rare to have less (Example: 4-man squad is not uncommon)

That's it for now. Whew...