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.

BitcoinDark is a fork of Bitcoin with a poorly defined purpose and use case. BitcoinDark is based on the InstantDEX protocol, a decentralized exchange for BitcoinDark and other cryptocurrencies supported by the project. The platform is also supposed to include a Pegged Asset Exchange (PAX) to allow users to buy and sell pegged assets – including fiat currencies, commodities, ETFs, and stocks.
BitcoinDark is a Proof-of-Stake (PoS) currency that has gained a significant market cap, but the project has failed to show how its vision will be implemented or how it will add value compared to other blockchain projects.

DigiByte is a a blockchain platform that places an emphasis on security and block speed. DigiByte has one of the fastest block speeds of any public blockchain and uses an innovative consensus protocol with 5 mining algorithms. This prevents mining centralization and also minimizes the chances of security breaches. DigiByte transactions are limited in size and scope to increase speed, efficiency, and throughput.
DigiByte hopes that these innovations will provide the ideal blockchain infrastructure for a range of applications within the IoT and AI fields, that require a high degree of security and fast block speeds.