Proof-of-Stake (PoS): Beacon and Casper are the 2 PoS solutions that aim to improve how new Ethereum coins are mined and how transactions are validated. In PoS, there is no mining which means there is no block reward; the block creators are called Forgers (instead of Miners as in PoW). They are only being incentivized with transaction fees. The Forgers of the next block are elected through a random procedure according to the Forger’s stake (amount of coins the Forger stakes) and age.
Ethereum Sharding is the process where the entire state of the network is split into a number of partitions called shards that contain their own independent piece of state and transaction history. This addresses issues of scalability and transaction speed and stops one app from slowing down the network.
Ethereum eWASM allows code to execute faster by expanding the coding options and capabilities for the Ethereum Virtual Machine. Ethereum Plasma is an extra layer that sits on top of the network to handle massive amounts of transactions. It is basically Ethereum’s version of Bitcoin’s Lightning Network.
Ethereum Raiden, like Plasma, is categorized as an off-chain scaling solution, and therefore can also be compared to the Lightning Network. Rather than processing the transactions on the main blockchain, Raiden uses state channel technology to move transactions off-chain and open a separate payment channel.