What is Ethers.js?

from official documentation

The ethers.js library aims to be a complete and compact library for interacting with the Ethereum Blockchain and its ecosystem. It was originally designed for use with ethers.io and has since expanded into a more general-purpose library.

Features

• Keep your private keys in your client, safe and sound

• Import and export JSON wallets (Geth, Parity and crowdsale)

• Meta-classes create JavaScript objects from any contract ABI, including ABIv2 and Human-Readable ABI

• Connect to Ethereum nodes over JSON-RPC, INFURA, Etherscan, Alchemy, Cloudflare or MetaMask.

• Complete functionality for all your Ethereum needs

• Extensive documentation

• Large collection of test cases which are maintained and added to

• Fully TypeScript ready, with definition files and full TypeScript source

• MIT License (including ALL dependencies); completely open source to do with as you please

What is Web3.js

from official documentation

web3.js is a collection of libraries that allow you to interact with a local or remote ethereum node using HTTP, IPC or WebSocket.

Features

• Get Ethereum Node Information

• Check User’s balance

• Transfer Ether from “A” to “B”

• Check whether a transaction has been confirmed or not

• Web3.js is asynchronous

• Interact with ABI, etc...

Difference between Ethers.js and Web3.js

source

While web3.js provides a single instantiated web3 object with methods for interacting with the blockchain, ethers.js separates the API into two separate roles. The provider, which is an anonymous connection to the ethereum network, and the signer, which can access the private key and sign the transactions. The ethers team intended this separation of concerns to provide more flexibility to developers.

Instantiating provider with MetaMask wallet

web3

const web3 = new Web3(Web3.givenProvider);

ethers

const provider = new ethers.providers.Web3Provider(window.ethereum)

Getting balance of account

web3

const balance = await web3.eth.getBalance("0x0")

ethers (supports ENS!)

const balance = await provider.getBalance("ethers.eth")

Instantiating contract

web3

const myContract = new web3.eth.Contract(ABI, contractAddress);

ethers

const myContract = new ethers.Contract(contractAddress, ABI, provider.getSigner());

Calling contract method

web3

const balance = await myContract.methods.balanceOf("0x0").call()

ethers

const balance = await myContract.balanceOf("ethers.eth")

Finally Ethers.js or Web3.js ?

Ethers.js is a lighter, developer-friendly library with a solid background. it is maintained just by a small group, which limits the development of the library.

On the other hand, Web3.js is the most used Ethereum JavaScript library. While also widely used, it lacks the breadth and depth of Ethers documentation and may not be the best solution for early Web3 developers.