RE: 1/8-1/10 motor/ESC difference New to Brushless
In not a pro but ill answer what i can.
1/10 scale motors are usually 550 size, which i believe is 55m.. 1/8 scale motors are about 78mm.
Its all about being able to fit in the car/truck.
Gearing is, there are 2 gears, small one on the motor is the pinion, the large one inside the car is the spur. If you have a 20 pinion and a 100 spur you are running at 5 ratio. Usually the higher the better from what i get. If you go lower like a 30/100 you will have a higher top speed / but higher top temps.
usually off road you want a lower KV, like 2-3000 kv if good.
On- road you would want higher.
My friend messed up and has a 5500 kv in a buggy and his car shuts off with heat problems all the time and his batterys swell alot.