The Graph Token is the native currency of the The Graph ecosystem. Their goal is to create an indexing protocol for querying decentralized networks, and allow anyone to publish open APIs, called subgraphs, which will make this data more accessible. These subgraphs can be composed into a global graph, and can then be transformed, organized, and shared across applications for anyone to query with just a few keystrokes.

Holo is a decentralized hosting provider that is built on top of Holochain. DApps can be set up and deployed with Holo hosting, as a decentralized alternative to Amazon Web Services, or other centralized hosting solutions.
Holochain is a protocol for creating decentralized Apps and is different from blockchain protocols in several ways. The main difference being that Holochain takes an agent-centric approach to their consensus mechanism, and has a different approach to validating value transfers.
The HOT token is used for paying for hosting services on Holo, and users can be paid for offering their computing resources.