Stellar is an open-source cryptocurrency network launched by non-profit Stellar Development Foundation. The currency itself is called Lumen (XLM). Some experts note that this asset has similarities with Ripple because of its quick and cheap transactions.
The Stellar network is guarded by the special contract that doesn't temporarily allow holders of big amounts of Lumen to sell it. Stellar works as an exchange platform where Lumen is used to pay a small exchange fee. The project has a high level of decentralization and provides equality for all of its participants. It has one of the biggest market capitalizations.
IOTA is a distributed ledger and cryptocurrency created to process operations between devices of the Internet of Things. IOTA was launched in 2015. The project is based on an unique directed acyclic graph (DAG) instead of a blockchain. DAG uses a Tangle technology which provides unlimited scaling opportunities and free and fast transactions. The project is backed by non-profit IOTA Foundation. Besides, IOTA ecosystem has its own data marketplace available both for companies and individuals. IOTA quickly gained strong partnerships in the tech industry (including Volkswagen and Bosch) and high market capitalization (by the end of 2017 IOTA reached top 5 list by its, market cap although now its position is lower).