Watch discussion is dense with terminology that mostly describes a small number of straightforward mechanical arrangements.
Quartz
A battery sends current through a quartz crystal, which oscillates at a very precise frequency, which is divided down to drive the hands.
Accuracy is typically within seconds per month, which is far better than any mechanical watch.
It requires a battery change every few years and essentially no other maintenance.
Which makes quartz objectively superior at telling the time, and that is worth stating plainly before discussing everything else.
Mechanical
A wound spring releases energy through a gear train, regulated by an escapement and a balance wheel oscillating at a fixed rate.
Accuracy is typically measured in seconds per day rather than per month.
It requires servicing every several years — disassembly, cleaning, lubrication, reassembly — which costs a meaningful amount.
Nobody buys a mechanical watch for accuracy. They are bought because the mechanism is interesting, which is a legitimate reason and should be stated as such.
Manual against automatic
A manual movement is wound by turning the crown.
An automatic winds itself from wrist motion, via a weighted rotor that turns as the arm moves.
Automatics are thicker because of the rotor, and they stop after a day or two of not being worn.
Power reserve — how long a fully wound watch runs untouched — is a specification worth checking, and it varies from around forty hours to several days.
Beat rate
The frequency of the balance oscillation, quoted in vibrations per hour.
Higher rates generally give better accuracy and produce a smoother sweep of the seconds hand.
Lower rates use less energy and give longer power reserve, and reduce wear.
The sweeping seconds hand people associate with mechanical watches is actually a series of small steps, and the beat rate determines how small.
Complications
Anything the movement does beyond showing hours, minutes and seconds.
Date, day, moon phase, chronograph, second time zone, power reserve indicator, perpetual calendar.
Each adds parts, cost, thickness and servicing complexity.
A chronograph is a stopwatch, and the mechanism to start, stop and reset a hand without disturbing the timekeeping is genuinely difficult, which is why chronograph movements command a premium.
In-house against supplied movements
A distinction given enormous weight in enthusiast discussion.
Some brands make their own movements. Many use movements from specialist manufacturers, sometimes modified.
Supplied movements are frequently extremely reliable, well understood by every watchmaker, and cheap to service because parts are available.
In-house movements may be better, may not be, and are generally more expensive to service because only the manufacturer has parts.
Which means the practical case for in-house is weaker than the marketing suggests, and the case for it is mostly about what you find interesting.
Certification
Independent chronometer certification tests a movement against defined tolerances in multiple positions and temperatures.
A certificate means the movement met a standard, which is real information.
Several brands apply their own internal standards that are stricter, and those are self-assessed rather than independent.
Water resistance
The most commonly misunderstood specification.
The depth rating is a static pressure test, not a swimming depth. Movement through water generates pressure well above the static equivalent.
Which is why the practical guidance is considerably more conservative than the number suggests.
Gaskets also degrade, so resistance on a watch that has never been serviced is not what it was when new. Pressure testing is inexpensive and part of any service.
What actually determines cost
Case finishing, movement decoration and brand position account for far more of the price than functional differences do.
A well-finished case with sharp edges and alternating polished and brushed surfaces takes considerable hand work.
Whether that is worth paying for is a preference, and it is at least a preference about something real, which is more than can be said for a lot of pricing in the category.
The case and crystal
Where a large share of the perceived quality sits.
Stainless steel grades differ — a higher grade resists corrosion better and is harder to machine, which is why it costs more.
Titanium is lighter and scratches more easily. Precious metals are heavy and soft.
Crystals are acrylic, mineral glass or sapphire. Sapphire is far harder and resists scratching almost entirely, and it shatters rather than deforming under sharp impact.
Acrylic scratches constantly and can be polished out at home, which is why it persists on some designs deliberately.
Servicing reality
The recurring cost nobody mentions at purchase.
A mechanical service involves complete disassembly, cleaning, replacing worn parts, lubrication and regulation, and it is skilled hand work taking hours.
Intervals of five to seven years are typical guidance, and watches run considerably longer than that before problems appear, which is why the guidance is widely ignored.
Running a watch with degraded lubricant causes wear that is expensive to correct, which is the argument for following it.
Independent watchmakers frequently charge substantially less than manufacturer service centres, with the trade-off being parts access for some brands.