I understand there are 2 main types of motors: brushed and brushless motors. How can you tell visibly what type of motor you have without researching/reading the manual?
As a general rule-of-thumb, brushed motors usually have two wires, while brushless motors generally have three.
Brushed motors are generally thin silver cylinders with a shaft that look like this:
Photo source: https://oscarliang.com/fpv-micro-quad-beef-board/
Brushless motors, however, will generally have visible copper windings and, most often, have the outside or ‘bell’ rotate:
There are differences - you might not always be able to see the brushed motor as some drones use gearboxes to increase torque, so another way to tell is that if you can see the wires, brushed motors have two and brushless motors have 3.
You will also not very often see brushless motors on a drone using gears, however it is common for brushed motors to have them.