Novacoin is a hybrid Proof of work (POW) / Proof of stake (POS) decentralized peer-to-peer cryptocurrency.The Proof of Work part of Novacoin is based on the Scrypt hashing algorithm. Proof of Stake contributes to the coins energy efficiency, as there is no need for nodes to contribute mining power to part of the money creation process. As of now, Novacoin is set to be capped at 2 billion coins. However Novacoin stated that the cap limit may be lifted if the situation requires it. It looks very much like a variation of Sunny King Peercoin.
Boom Token is a social experiment. Blockchain gives us an opportunity to create this deflationary currency, and the deflation mechanism is fully based on smart contract. The basic rules are as below: There were originally 1,000,000,000 Boom in existence. Each on-chain Boom transaction completed, 1% of the transaction amount burned. There will never be newly minted Boom.