The blockchain is at the core of cryptocurrencies. In short it represents a public ledger of who owns what.
Ethereum based tokens go by the ERC-20 standard, and allow third parties to launch custom tokens on top of the Ethereum network.
For technical details: https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md
Stellar tokens, also known as assets, are custom tokens utilized within the Stellar network.
Smart Contracts is code that is executed on the blockchain network. Several coins allow smart contracts. Differences between them is based on contract code language, speed and costs.
dApps is short for decentralized apps. It allows programs to execute code on the blockchain network.
An overiew: https://www.stateofthedapps.com/
The lightning network is a protocol on top of the blockchain, allowing instant transactions over a payment channel.