Explain void vs undefined

In TypeScript, void is a type that represents the absence of a value (the value is not important).

function fnVoid(): void {
    let value;
    console.log('some logic with value');
}

The void type is used to indicate that a function does not return a value, or that a variable or expression has no value.

function fnUndefined(): undefined {
    let value;
    console.log('some logic with value');
    return value;
}