Ethereum vs Web3j: What are the differences?
What is Ethereum? Open source platform to write and distribute decentralized applications. A decentralized platform for applications that run exactly as programmed without any chance of fraud, censorship or third-party interference.
What is Web3j? Lightweight Java and Android library for integration with Ethereum clients. It is a lightweight, highly modular, reactive, type safe Java and Android library for working with Smart Contracts and integrating with clients (nodes) on the Ethereum network. This allows you to work with the Ethereum blockchain, without the additional overhead of having to write your own integration code for the platform.
Ethereum belongs to "Blockchain" category of the tech stack, while Web3j can be primarily classified under "Java Tools".
Ethereum is an open source tool with 4.84K GitHub stars and 1.73K GitHub forks. Here's a link to Ethereum's open source repository on GitHub.