Hi Brandon.
Yes, the way armature animation data is stored (at the moment....it's changing in the near future), is that it is contained inside a datablock called and "action".
If it's an armature, the bones names will need to be the same. but you can just apply any animation to any character you like.
However the result might not be what you expect if the rigs are different. For example, you might have a character with short legs, but with all the same bone names as a character with long legs. Technically you can make them use the same animation data, but it isn't going to work very well.
But if the characters are essentially the same except for the textures. Then it will work perfectly.
Hope that helps clear things up.
Also animation layers is an addon that helps speed up the process of using the NLA editor to combine (or layer) animations.
It just automates many of a laborious steps of doing it manually.
It's a great addon.
Would the animation data change better for the future if you know? I assume it would only make things easier at least I hope. I hear the blender devs are going to really focus on animation in 2025. But yea I may need to do the same walk cycles for the different characters as the rig creator has multiple character types to switch between in the same package, I will leave a link so you can know what I mean. You can skip to 9:50 where he showcases it. They may not have the same bone names after switching body types.