Eternal is a Japanese cryptocurrency project that consists of Eternal Coin (XEC) and Eternal Token (XET). The project appears to be primarily focused on remittance payments, but can also be used as a medium of exchange for other purposes. XEC holders receive weekly dividend payments, and can only be traded through the company's authorized exchanges. XET was created to allow users to trade XEC on other crypto exchanges. 1 XET=10 XEC.

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.

Ethereum is a blockchain-based computing platform and operating system whose core innovation is enabling smart contracts. Ethereum's smart contract functionality, and versatile scripting language, have made it the most popular network for creating decentralized applications. What makes Ethereum different from Bitcoin is that its primary purpose is to serve as a general purpose blockchain for creating DApps, and not as a payment network. Ethereum was created by Vitalik Buterin. It was launched in July 2015 and has become one of the most important blockchain platforms in the industry. Ether is the native currency of the Ethereum blockchain and can can be used as a transfer of value, as well as a form of compensation for mining. The Ethereum Virtual Machine (EVM) executes scripts using a network of public nodes. "Gas" is used as an internal transaction pricing mechanism that decides how resources are used on the network.