What's the difference between a Voice Actor and a Voiceover Artist?

Technically, there is no difference.

Anyone who does voice overs can be considered a voice actor. It's really more of a branding choice.

A voice actor in the animation and games realm might want to emphasize their acting ability more, which is why they will use the term "voice actor" to refer to themselves.

Somebody in the commercial and corporate space may want to use "Voice Over Artist", as less clients associate think of voice overs as acting in that space, and are perhaps under the impression that they don't want an actor, but a nice voice.

Some people even call themselves "Voice Over Actors".

This is really more about perception though, as all voice actors/voice overs/narrators perform a role.

Whether it's an explicit character (video game, audio drama, animation), implied character (commercials, corporate, brand videos) or a narrator (documentaries, audio guides), there is always some element of performance.

We're all voice actors whether you like it or not!