All-knowing
The audience is all-knowing in the sense that they are fully aware of context, content and interaction. Through their general knowledge and by providing very clear instructions, information and very recognizable visual cues. This can be done to give the audience all the knowledge they need to follow your narrative. By giving the audience this role you take away the possibility to have strong elements of surprise in your project. But you will able to rely on the fact that they already have all knowledge to go further in depth into a subject or into interaction. It can still be really engaging, but it won’t give the audience big realizations throughout the project; you already informed them about everything. This doesn’t mean that your project will become dull, it’s a really good way to reinforce emotions and create more interest and/or enjoyment.
Spectator
A spectator is someone who is presented with information in a linear path, as the designer intended. The content doesn’t necessarily have a linear narrative, but the way in which it’s presented in does. The spectator doesn’t interact with what’s presented in front of them, what is presented is exactly the same for every spectator. The difference in how it’s perceived by the spectator relies solely on their general (intrinsic, explicit & tacit) knowledge, interests and their choice of how they spectate (duration, position, attention, etc.).