I've seen tokens referred to as "protocol tokens" and "dapp tokens", as far as I can tell they are on in the same. Maybe a protocol token is simply a dapp token with a published ABI?
There's even this page that claims to differentiate them in the title, but isn't clear to me after reading it a few times.
(bonus question) I've seen a few people refer to "overlay networks". Is a side-chain the same as an overlay network? As far as I can tell, no one has created a blockchain overlay network, and I'm not even sure what one would look like.
Wikipedia defines an overlay network as: "a computer network that is built on top of another network. Nodes in the overlay network can be thought of as being connected by virtual or logical links, each of which corresponds to a path, perhaps through many physical links, in the underlying network."
A don't see a sidechain satisfying this. A sidechain isn't on top of another blockchain, it has it's own nodes.