If statement vs function blocks for var keywords

My question is why is a variable (when using var keyword) accessible outside the if statement block, but not outside the function block? Consider this code:

let age = 30;

if (true){
    let age = 40
    console.log('inside', age)  //logs inside, 40//
    var name = 'shaun'
}

console.log('outside if loop', age, name) //logs outside if loop, 30, shaun //

function test (){
    var xyz = 'ashley';
    console.log(xyz)

}
test ()

console.log('outside function', xyz) //throws an error//

Thank you for your time. Any insights would be appreciated!