As per chilmistressfreia, yeah, they are entirely different entities in RPG Maker MV. If you ever see a limitation with the software like what you’re seeing, you can usually rest assured that there’s a script for that. That, too, is a rabbit hole.
I use a third-party character generator to make my battlers, but you can use the battlers’ PNG files that you save in [SV_actors] as a basis for enemies if you install Yanfly’s “Animated Sideview Battlers”, and then use the notetag <Sideview Battler: filename> on the enemy. It would essentially replace the image of the enemy with an animated battler sprite in-game, flipped to face the player. Note that if you are new to RPG Maker MV you should not really go crazy with the scripts, just get what you need, tune the plugin to your needs, and learn the basics to code.