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.

Kadena is a software development company that builds blockchain-based platforms for a range of businesses. They develop purpose-built blockchain solutions for their clients by using proprietary solutions that are aimed at being both secure and scalable. Kadena offers both private and public blockchain platforms, with smart contracts written in the Pact programming language. They've also developed an innovative proof-of-work architecture called ChainWeb that could have a variety of applications.
Kadena's founders have experience working for the U.S. Securities and Exchange Commission (SEC) and JPMorgan Chase Bank. The company has raised significant funding and is well positioned to be play a big role in developing future blockchain solutions for large financial institutions.

Blockstream is a private, for profit, blockchain technology company, that has played a key role in helping to develop, and fund, many of the key features of the Bitcoin Core platform. Blockstream is focused on developing bitcoin applications and has raised significant funding from several large investment funds. The company also employs several developers that are very influential within the Bitcoin Core development project. This, as well as being of Bitcoin's largest donors, has led to some criticism about conflicts of interest.
Blockstream is developing a number of Bitcoin applications that are intended to encourage adoption and improve transaction times on the bitcoin network. Their primary focus is on Sidechains, which are are extensions to existing blockchains that improve their functionality. The company is also working closely with industry leaders to create the Bitcoin Lightning system that will support higher trading volume and faster transactions on the bitcoin network. Blockstream is also developing a data feed, satellite network, and other applications that they hope will make blockchain more accessible.