What is the difference between a voice actor and a voice-over?

There is a lot of overlap between these roles, and some professionals do both. The difference lies mainly in how the voice is used:

• A voice-over speaks as an observer, provides commentary and usually addresses the viewer directly.
• A voice actor is part of what is happening and plays a role in it.

But when a commercial needs a strong character, the voice-over can act too. And the voice actor can record a voice-over. Not everyone can do both.