difference between drone and helicopter
 

Hi. It would be so nice if someone could shine light on questions which have eluded me for years. Why do drones have 4 propellers usually? If 4 is better then why do helicopters only have one (plus tail)? Why don't they build helicopters which have cameras and same functionality than drones? (or do they). These questions apply to RC and to full size ones. Thank you kindly.

Quads take a flight controller that took a while to evolve to a size and cost that made hobby drones practical, we have been flying conventional RC helis for many years, me since the late 70's. Even the tail rotor gyros and flybarless flight controllers have evolved. When I started I worked for a week on my heli to get a couple of 5 minute flights before something broke. Now its all solid state and flybarless.