maticjs has two parts -
The Main library has the core logic and provides different APIs. The user interacts mostly with this library.
npm i @maticnetwork/maticjs
Ethereum library allows us to use any favourite ether library. It is injected into maticjs using plugins.
matic.js supports two popular library -
npm install @maticnetwork/maticjs-web3
npm install @maticnetwork/maticjs-ethers