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.
Viacoin is a Script-based cryptocurrency derived from Bitcoin. Similar to Bitcoin and other cryptocurrencies, Viacoin is also an open-source project. Viacoin aims to be the cryptocurrency of future, by integrating many innovative key technologies such as SegWit, APoW, Lightning Network, Dark Gravity Wave, and more. Viacoin claims to allow 25 times faster transactions than Bitcoin. It can be merged mined with the other Script cryptocurrencies like Litecoin, This is done by using an Auxiliary Proof-of-Work (AuxPoW) algorithm. Every six months, Viacoin halves the block reward that is given to users for Viacoin mining, resulting in a low inflation rate of Viacoin. Check out CoinBureau for the complete review of Viacoin.