Radium is a Proof-of-Stake cryptocurrency that serves as the base blockchain for SmartChain Core which expands the utility of Radium far beyond that of a standard coin, with features such as identity-address linkage, proof-of-existence, file checksum verification and validation, and decentralized elections and voting. All of these features exist in a 100% distributed data-layer within the Radium blockchain.
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.