Nxt is a blockchain platform developed by Jelurida, which is also developing the Ardor blockchain. Nxt's goal is to improve upon existing blockchain platforms with a modular toolset that enables users to create their own digital assets that can be listed on decentralized marketplaces. Nxt also features community driven voting mechanisms and has an architecture that separates the blockchain into parent and child blockchains.
The network is powered by the NXT token and has a Proof-of-Stake (PoS) consensus mechanism.

NEO, formerly known as AntShares, is one of the leading smart contract enabled blockchain platforms that allows for the development of digital assets. Similar to Ethereum, NEO uses two different tokens: NEO and GAS, each of which have a specific purpose on the network. NEO tokens give holders a share in the ownership of the NEO blockchain, and when they are held in a compatible wallet, they are rewarded with GAS tokens. NEO has a Delegated Byzantine Fault Tolerance (dBFT) consensus algorithm that has uses some features of PoS, and is designed to be more scalable than other consensus mechanisms.

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.