In company of heroes there are 2 factions, each contain 2 armies and each army has 3 special tech trees.
One of the most popular armies among new players, the American army is very easy to handle as it can adapt to any situation the axis can throw at them. The 3 tech trees are: Infantry, Airborne and Armor. they have a unique experience level up as they survive they become more powerful.
Infantry specializes in Rangers, riflemen that automatically comes equipped with 2 bazookas and can be upgraded with Thompson Submachine guns making them Infantry killers and Light-med tank killers. Their infantry are produced much faster. Also in the Infantry commander's arsenal are Howitzers; long range artillery that all Allies love to hear and Axis dread. They also can use Howitzer barrages as a power for a supplies cost.
Airborne as the name explains itself allows the player to use paratroopers to infiltrate enemy lines. They can be upgraded with recoilless rifles that are good against tanks. They are weak against assault troops but with democharges and grenades can prove to be formidable; they also can use P-51 mustangs to strafe, bomb, and scout the land, and if the enemy are using tanks they can paradrop AT-guns and supplies that give fuel and supplies bonus and leave a MG and mortar against pesky infantry.
Finally Armor commander specializes in Armor units. It can produce tanks faster, and has the ability to requisition Pershing Tanks, the American Answer to the Tiger tank. It can also receive Calliopes. The armor general can capture points with Light vehicles, repair their tanks on the move, and instantly replace tanks with War machine as long as it is active.
The British is technically Turtle as they specialize in a lot of Defensive Structures. They are weak in Early game as they can only produce Infantry Sections and Bren Gun carriers, but as they advance to Mid-game they unlock Powerful Defensive structures and by Late-game easily dominate any pesky Krauts that enter in their range. They can also use officers to buff the units near them in offence or defence. The British company commanders are the Royal Engineers, Artillery, or the Royal Commandos.
Royal Engineers: who specialize the Pure turtling. allows you to requisition Churchill tanks, which are essentially Cromwell Tanks with the armor equivalent of a Tiger, they are 3 Churchill you can use. Normal Infantry support Churchill, with a Vicker's MG and a 75mm cannon it can be upgraded with a Anti-mine field Plow, the 2nd Churchill is the Petard Churchill with a little munition launch a large Petard round that can destroy literally any building in 1-2 shots, damage tanks, and kill massive groups of infantry, but it's turret's slow and it takes 3-4 secs to launch needing perfect timing to be lethal. finally is a Flame Churchill like the Normal one but instead of a Vicker machine gun it has a flamethrower, paired up with it's turrets knock out any light tank or Panzersherk Infantry. Finally it's support are, Stronger Defense structures, The ability for a tank to Hulldown, which puts it in a trench and increase it's survivability, or Triple all Resources that you secured and increase your pop cap.
Artillery: it's name easily alludes what you are suppose to do, allowing you to increase the range of your 25 pounder guns making them shoot almost anywhere on the map, also brings in M1 Priests, mobile Howitzers, also add an ability that allows your Captains and officers to deploy pinpoint off-map arty, or smoke. The abilities that can be used are Overwatch, making your arty attack enemy units with Air-burst shots that are lethal to infantry and light vehicles. Creeping barrage which makes a barrage creep towards a direction, Fatal if 3-4 attack at the same point, and Counter-battery, which sets your Arty to automatically barrage any Arty that fires.
Commandos: the British equivalent to the American Airborne. Which allows the player (you) to harass the Germans until they die, or leave. It allows you to Glide in Commandos, Tetrach Tanks, and a barracks that can build specilised commando weapons teams for you to use. Your powers are a Triangular detection that if you build 3 stealthed radio detectors in a triangle all units inside are visible, Decode messages so you can see what your enemies are building or talking, and Fake Smoke Barrage allows you to send red color barrages, OR real ones if they get too cocky.
Their forces include infantry, like the conscript Volksgrenadier militia, and mid-tier infantry like grenadiers, Waffen-SS stormtroopers to elite squads of soldiers awarded the Knight's Cross. Axis field operations can be supplemented by specialized equipment like the Nebelwerfer rocket artillery. Axis armor is far less mobile, but in direct combat generally superior, fielding equipment like StuG IV, StuH 42 assault guns, Panzer IV and Panther tanks. With specialized commander focus, Axis forces can deploy superior units, like the Tiger I tank or the "King Tiger" Tiger II tank. They are very powerful and considered overpowered late in the game; as time passes by, their power expands as their veterancy gets upgraded.
Blitz: which in German means Lightning specialize in Fast attacks, they are given Storm Troopers, the axis equivalent of Rangers, except they can go camouflage. Stuh 42 Stugs with a nasty Howitzer that can blow up any buildings or infantry in it's way NOTE they are not to be confused with Allies howitzer they can't shoot across the map. Also the ability to bring in Tigers! Their abilities allow Infantry squads to "Assault" buildings or Squads with a barrage of Grenades, Start a Blitzkrieg making all units to shoot and move at a increase rate, and tanks to run over all Barriers with no penalty.
Terror: as it's name implies it's to Scare the CRAP out of those Yankees or Limeys. all your units becomes fanatics with increase attack rate and damage with no regards to their safety, they can firestorm Targets killing any infantry or damaging any light vehicles in the area, or call in a V-1 Rocket Blowing up anything in the game. they can also call in once a game a King Tiger the deadliest tank in the game, Warning once it pops out you can't call another one. it can Tank shock infantry into retreating or call in a smoke barrage if it gets too hot. Special Tip be very careful on how you use it and don't rush it in towards British AT 17 pounder emplacements without backup or it will die. but it's health allows you to send in units for a V-1 strike
Defence: the Axis equivalent to the British, all their buildings in the HQ area have machine guns, your bunkers can replace depleted squads, you can call defensive arty, that won't hurt your buildings but damage all enemy units in the area, build Flak 88's that can knock out any tanks the allies send in, or call in a rocket barrage then they'll know who's talking. also you can give defence bonuses to your units in your sectors and see a large portion of land around Points.
The Panzer Elite mainly focuses on speed and vehicles. They cannot build static defenses; but instead they use halftracks to hold territory and increase resource income. Unlike other players' halftracks, Panzergrenadiers (the standard Panzer Elite infantry) can fire from inside the vehicle. However, since the Panzer Elite halftrack doesn't have a closed top, the infantry inside are vulnerable to enemy fire. Panzergrenadiers are also unique for being able to upgrade to use Gewehr 43 semi-automatic rifles, StG 44 assault rifles, or Panzershreck anti-tank weapons. Their Panzergrenadiers also double as the Panzer Elite, being capable of construction and repairing vehicles.
Another unique feature to the Panzer Elite is the fact that they can recover destroyed axis vehicles and tanks using the Bergetiger, provided the wreck of the vehicle had not been completely destroyed. A recovered vehicle that belonged to an ally will be returned to under their control, not the recovering player.
Scorch Earth: Allows the player to use Scorch earth tactics. It gives your units the ability to booby trap points and buildings for free, and to build road blocks to detour enemy tanks to kill zones, sector arty, which bombards any enemy unit in the selected sector. If you are being bombarded by the pesky 25 pounders or enemy howitzers you can call in a Hummel, a mobile howitzer piece.
Tank Hunter: As the name implies turn your entire army into professional tank killers. Using Tank awareness it allows your units to notice enemy tanks from farther than their normal line of sight. It also allows you to use Teller mines, that can kill light vehicles in 1 blow or any tank with a couple, but costs 50 munitions and it only affect Vehicles not infantry. You are also given AP rounds so anti-tank vehicles have increased damage. They may also use double Panzerschrecks that gives two Panzerschrecks to infantry squads, instead of 1. Reinforcement-wise you are given Hetzers - cheap, fast and powerful Tank hunters that can camo for additional damage, and in the End game stage you are given the JagdPanther - similar to the King tiger that you only get it once a game, but it can kill any tank in a couple of shots, but beware it's vulnerable to fast light tanks and infantry, so back it up or make your teammate get a King tiger and that's game!
Luftwaffe: The German equivalent to the Airborne and Commandos, it gives you control of Germany's Elite troops, Fallschirmjaeger who may spawn out of any building and are equipped with assault rifles for long and mid-range kills. You can call in Luftwaffe squads, who provide the only static defenses such as flak 88 and Flak guns. If the enemy can get through those use butterfly bombs - anti infantry mines, used in conjunction with Teller mines can make a nice defense. If the Yankees are raining like cats and dogs call in the Wirbelwind similar to an Ostwind but fires more bullets, because it has four cannons instead of one. and if tanks are coming call in Heinkel Bombers to bombard any enemy tank, buildings, or infantry in that area.