All units are at least .4 so that those that are local and levy (almost all peasants) have still .1 x unit numbers.
Superior, Elite, Exceptional are usually written under the dictionary or category description;
dictionary Feudal_Knights ; Feudal Knights
category cavalry ; elite mounted melee, early lance/sword
Many of the descriptions only contain 1 letter- f, u, m, etc... so you have to read carefully. If you like it is easier to spell it out and save for the next person. Sometimes there is nothing in either description or dictionary about the type, so then consult pressdat or ask me, PB, or K/T though sometimes in RC there is no clear answer so we have to think of the history. Many times if there is nothing noted then assume the units are Average unless there is something about them that seems either very good or that they might be militia.
Pavise Spearmen for example are militia but they are also early pro due to equipment and drill(training in game mental stats which makes them more resistant to rear charge or death of general)
There is no category 'peasant militia' the closest would probably be local levy (basically locals conscripted for emergency defense). If they are a levied militia it means they have some very basic training and maybe some weapons not well maintained given them but usually they have low mental stats and the trained mental stat which helps offset minor shocks but they will still flee pretty easily.
So the various Quality levels are-
Exceptional (bodyguards, a few famous units, etc)
Elite (most often high roster troops, high class units, many late pros due to training are elite)
Superior (better than average for their era but not elite- all knights and pros are a minimum of 'superior' except Luchniki and a couple others- personally I think knights and pros should all be at least superior)
Average (just what it says, probably about 1/3 of EDU is Average)
Levy (no training or minimal training, cheap emergency units)
Mercenary (usually a bit better than average unless they are locals simply due to experience and survival of the fittest, can be elite and sometimes legendary/exceptional like Swiss or Catalans/Varagnians- if on a faction roster treat them as Urban Late Pro- basically add 1 to cost but retain the 1 turn to train instead of 4 turns for late pro as they are hired already trained- if the unit is available only as mercenaries hired in the field just add 3 and the / 3 / 2 for upkeep)
There are also unit types that are not necessarily tied directly to quantity but can indicate a minimum like early and late pro.
Urban (raised in an urban area so expect higher wages and often have better equipment than otherwise)
Rural (often have worse equipment but more likely to have stamina stats and due to distance cost more to gather for muster)
Local (close but not within city or travel, trade, ally within the region frequently so Pechenegs, Chudes, many AOR units are locals, usually a bit less stats but cheaper than roster units)
Feudal (men in vassalage to a lord or in a knights retinue so squires/sergeants/knights/bodyguards/huscarls, usually high mental stats but low availability and equipment covers a broad range, cheaper than many other units as part of the service is due by oath and class)
Missile (there are missile specialty units and some units which just open the battle throwing a small handful of weapons, the ones with small amount usually add little to cost of a unit since they can reuse or make their own missiles, dedicated archers are more expensive due cost of replacing arrows/bolts/gunpowder and the training/experience of the men)
Early Professionals (men who are active or more active than most Feudal or Local warriors and often provide their services for longer campaigns but aren't full fledged mercenaries nor fully maintained by a state, most religious orders would be ep and often Sergeants or Men at Arms- it is possible to be both Feudal and Early Pro)
Late Professionals (men whose sole task is to fight, standing armies that are paid to fight with no other obligations such as managing land, equipped by their employer and usually trained as well, they have greater availability than any other units and typically higher skills as they are professionals)
Knight (not necessarily a quality on its own but a type/class, knights even if serving as dismounted low armor infantry due to class received higher pay and also figure most have a horse just not using it so they don't have that extra cost)
Cavalry are treated specially as they are the most expensive combat arm other than artillery.
Light cavalry ride smaller, often higher stamina, and fleet of foot animals- they are lightly armed and armored and can often be locals or early feudals as well as mercenaries. Sometimes militia that could afford a horse. Often horse archers or missile cavalry. Light cavalry role in battle is to distract, harass, and pursue the enemy. Extremely vulnerable to missiles.
Medium cavalry can ride large ponies up to Arabians and usually are normal speed receiving neither penalty nor bonus to speed. Some medium cavalry receive stamina traits if they ride fine horses. Medium cavalry can fulfill any role on the battlefield at the cost of lower armor. Often heavy enough to beat light cavalry in melee and fast enough to chase them down medium cavalry can be heavy enough for a shock charge but won't last long in melee but are better than light cavalry fighting infantry. Missiles can take a toll on medium cavalry in many situations.
Heavy cavalry ride warhorses and usually have a 2nd horse for when not in battle and often a 2nd man to help maintain the gear and horses of the heavy cavalryman. Expensive to maintain and equip but can play a decisive role in battles. The man and as eras progressed, the horse are well armored at the cost of speed and heat penalties which causes them to exhaust quickly, the highest mass cavalry means they have an advantage in melee with everything other than elephants or other heavy cavalry. However due to slower speed and exhaustion sometimes medium cavalry used well can beat them though the medium cavalry is still bound to suffer large losses. Often suffer light losses to even heavy missiles and later eras are nearly invulnerable to missiles except bows fired at close range or guns.
Artillery and special units like Naffatuns or Siphonatores are the most expensive man for man of the crew due to logistics of building and maintaining the units and the cost of the supplies as well as the special skills of the men(usually some math and can read/write).