Bitcoin Diamond is a hardfork of Bitcoin that was created in 2017. Although the network's code preserves much of Bitcoin's original features, it aims to improve transaction speeds by implementing the Lightning network and increasing the storage capabilities of each block. The Lightning Network is a second layer payment protocol that works on the Bitcoin blockchain and is designed to place a large portion of the transaction data outside of the blockchain.

ZCoin is a privacy focused cryptocurrency built on Ethereum. The ZCoin protocol enables anonymous transactions with cryptography that utilizes Zero-Knowledge Proofs (ZKP). ZCoin increases privacy on their network by using a coin-mixer contract that wraps transactions in a serial number and destroying wrapped coins once they have been redeemed.
Zcoin was the first cryptocurrency to use a Merkle Tree Proof (MTP) as its proof of work algorithm. Merkle Tree Proofs are an innovative solution to achieving network consensus, and can increase transaction time while reducing the centralizing tendency of ASIC mining.

WhiteCoin is a cryptocurrency protocol with a Proof-of-Stake (PoS) consensus mechanism. WhiteCoin's (XWC) marketing materials place an emphasis on security and stability, but do not present details regarding their specific technical advantages or project goals.
WhiteCoin's payment network provides a high degree of anonymity and its PoS consensus model allows XWC coin holders to earn revenue by staking their holdings.