What is the difference between getSigner() and the value eth_accounts?

Question

This is not an issue but just looking for an explanation. I have the following code to get the contract data:

const provider = new ethers.providers.Web3Provider(ethereum);
await provider.send("eth_accounts", []);

const signer = await provider.getSigner();
console.log(signer);

const account = await ethereum.request({method: 'eth_accounts'});
console.log(account[0]);

const contract = new ethers.Contract(contractAddress, contractABI, signer);
console.log(contract)

Everything is working fine but I am confused on why when I log out the address for the signer variable, it shows as null but when I log out the account variable I get my address. If I swap the value of signer that is inside of the contract variable with account it fails but it succeeds with signer even though the address is null and I am able to see my contract functions.

Could anyone explain this or point me to docs that has a better explanation?

If it even helps, I am using MetaMask wallet and the full file code is written in react/typscript here:

import {useEffect} from 'react'
import contractABI from '../utils/contractABI.json';

declare const window: Window &
  typeof globalThis & {
    ethereum: any
}

export default function Create() {
    const {ethers} = require('ethers');
    const contractAddress = '0x261d5ADa2C89369E1AfCAA98d52dEb124DD9f0Ff'
    const addNewStudent = async () => {
        try {
            const {ethereum} = window;
            if(ethereum) {
                const provider = new ethers.providers.Web3Provider(ethereum);
                await provider.send("eth_accounts", []);
                const signer = await provider.getSigner();
                const account = await ethereum.request({method: 'eth_accounts'});
                console.log(account[0]);
                const contract = new ethers.Contract(contractAddress, contractABI, signer);
                console.log(contract)
                // const addNewStudent = contract.addStudent
            }
        } catch (err: any) {
        console.log(err);
        }
    }

    useEffect(() => {
        addNewStudent();
    }, [])
  return (
    <div>Create</div>
  )
}

Answer 1

A Signer in Ethers.js is an object that represents an Ethereum account. It's used to send transactions to contracts and other accounts. getSigners is used to get a list of accounts in the node you're connecting to.

eth_accounts is used to return an array that is either empty or contains a single account address. The returned address, if any, is the address of the most recently used account that the caller is permitted to access.

See:

https://hardhat.org/hardhat-runner/docs/other-guides/waffle-testing

https://docs.metamask.io/guide/ethereum-provider.html#events