Ethereum is a smart contract platform that enables developers to build tokens and decentralized applications (dapps). ETH is the native currency for the Ethereum platform and also works as the transaction fees to miners on the Ethereum network. Ethereum is the pioneer for blockchain based smart contracts. Smart contract is essentially a computer code that runs exactly as programmed without any possibility of downtime, censorship, fraud or third-party interference. It can facilitate the exchange of money, content, property, shares, or anything of value. When running on the blockchain a smart contract becomes like a self-operating computer program that automatically executes when specific conditions are met. Ethereum allows programmers to run complete-turing smart contracts that is capable of any customizations. Rather than giving a set of limited operations, Ethereum allows developers to have complete control over customization of their smart contract, giving developers the power to build unique and innovative applications. Ethereum being the first blockchain based smart contract platform, they have gained much popularity, resulting in new competitors fighting for market share. The competitors includes: Ethereum Classic which is the oldchain of Ethereum, Qtum, EOS, Neo, Icon, Tron and Cardano. Ethereum wallets are fairly simple to set up with multiple popular choices such as myetherwallet, metamask, and Trezor. Read here for more guide on using ethereum wallet: How to Use an Ethereum Wallet
IOTA is a distributed ledger for the Internet of Things. The first ledger with microtransactions without fees as well as secure data transfer. Quantum proof. IOTA is a ground breaking new open-source distributed ledger that does not use a blockchain. Its innovative new quantum-proof protocol, known as the Tangle, gives rise to unique new features like zero fees, infinite scalability, fast transactions, secure data transfer and many others. IOTA is initially focused on serving as the backbone of the Internet-of-Things (IoT). IOTA is a cryptocurrency that has no transaction fees and requires no miners in order to process transactions. It does, however, require some computational power to submit a transaction, making it perfect for machines to use as a currency and distributed communication protocol for the Internet of Things “IoT”. The main purpose of IOTA is to solve some of the major problems with Blockchain technology, the main one being that the bigger the Blockchain (such as Bitcoin), the slower, more expensive, and also more restricting it is to actually transfer funds. Another issue with the Blockchain is size, as more and more Blocks are added, the longer the Blockchain gets, and therefore the less amount of computers are able to mine it. Right now BTC is over 150GB long, and so is ETH. If this size increased tenfold, very few computers would be able to mine it at all. Making them relatively centralized (the top 2 Bitcoin mining pools own about 56% of hashing power).