One's a scam and the other isn't? I mean, it's just a question of whether the thing is legitimate, real, and non-fraudulent.

That's what I'm asking though. Are "protocol tokens" the same as regular tokens, technically speaking?

In the same way that mmorpg currency is.

A protocol token can actually be used to do something.

What is it then? How does it differ from regular tokens, from a technical point of view?

There is some program in existence which uses the tokens to fund or incentivise actually performing some useful action.

It's necessary for the network design.