Okay, what are these?
Companions come from The Companions’ Quarters, and provide a writer a means to have a companion that can be detailed without having to make an account for that companion. They essentially function as pets, meaning you can rp as them on the account you own them on.
Armies, in contrast, come from The Mercenaries’ Camp and allow for characters to have armies if they so desire.
What's the difference between the two?
Companions can have rich backstories and are also permanent editions to an account's inventory. They do not decay, and any equipment or spells they cast must be owned. They can also be rped as individual characters on the same account, albeit with limitations. A major drawback to companions is that you CANNOT command groups of them like an army, and you can only have 10 in a single thread at a time. Each companion must be treated individually when describing their actions, so there is no hive mind from a writer's perspective.
Armies, in contrast, can be directed as a hive mind, but cannot be given personalities. These are the typical, 2-dimensional NPCs you use every day in your threads. They also come with equipment/spells and decay after six months from purchase. A military unit can be ordered around by your character in thread and is subject to limited god mode protection.
Cool! So both come with equipment?
For the companion NPCs, assume that they come with the basic starting package associated with their classes. If you want them to have more specialized equipment, spells, clothing or items in general; then those items must be purchased.
Military units, on the other hand, come already armed and armored with the inclusion of spells. That said, any spellcasters that are military units are more heavily limited than companions in what they can cast, and you must pay attention to that(see question related to spells).
Why is there a decay timer on the military units?
This is meant to represent the wearing down of military units over time, due to battles lost, deserting, training, and people having to retire for various reasons. An army is not free. They have upkeep, and so the decay timer serves to enforce realism and balance.
What kind of spells can magical companions cast?
Companions and pets are allowed to cast most spells up to a cost of 700 silver and share spells with the main character(i.e. you don't have to purchase a spell more than once no matter how many companions use it). If a spell costs more than 700 silver in the shop, a companion can't cast it regardless of ownership for said spell. Also, conjuring spells are off limits to companions with the exception of spells like conjure food, summon companion, conjure magical weapon, and summon item in order to ensure fairness.
This set of rules is modified slightly for military units. Military units that can cast magic possess all the limitations of companions and pets(in terms of power, cost and conjuration), but a user does not need to buy spells in order for them to cast said spells. The caveat is that these units are also specialized in a single element and can only cast combat magic. The result is that they are weaker individually than a regular companion, but their numbers make up for that weakness.
You mentioned military units have limited godmode protection? What's that about?
Military units are in a unique position. They can't be outright slaughtered by anyone attacking them without the author's permission. However, they also can't be impervious to damage. This is a common sense boundary that you must understand with your rp partners and work out a compromise when combat occurs.