What exactly is the difference between 8 fps and 24 fps drawn-on-threes animations?

Is there any difference between an animation sequence drawn on threes (8 different drawings for a second of motion) that plays back at 8 fps and 24 fps?

As in after you draw 8 different drawings for a second of motion, which will be exported:

  • As 8 different image files for an 8 fps video
  • Vs as 24 image files which contain only 8 truly different image files (the rest are just graphical duplicates of those files) for a 24 fps video?
    (For the sake of argument let’s just forget the occasional need for drawn-on-ones drawings for smoother quick actions, and automated tweening, let’s just talk about pure frame-by-frame animation manually drawn on threes (or twos in the case of Western animation))

Moreover, is it correct to say most animations play at 8 or 12 fps or whatever while in fact they actually play 24 fps, only that every 3 or 2 of those frames are exact duplicates?

Also, which is the more efficient way to compose an animation sequence, concerning file size, computing power (using whatever program like After Effects, Premiere Pro, Animate, Harmony, etc.), playback quality and compatibility to different setups or broadcasting standards (23.976 fps, 25 fps, for European TV, for North American TV, for YouTube, etc.):

  • Play 8 or 12 image files at 8 or 12 fps;
  • Or play 24 image files (of which 16 or 12 are exact duplicates) at 24 fps?

I think it depends on the destination, if it’s for TV, I would recommend setting the scene at 24 fps and use the 8 drawings in all the frames you need. Video game animation is usually made at 30 fps, but you can set the fps you need for your specific project.

At the end, if the destination format is video, whatever you choose it should look very similar, I’d say choose whatever makes more sense to you.