Structural subtyping equivalence in Typescript

Question

In the function below, an object is being returned in the first function which typescript compiler complains about. While for the second function it doesnt complain. Why this difference?

    type  x = {
    name:string
}
type r = {
    name:string,
    age:number
}
//Invalid
function returnSomething():x{
  return {
      name:"abc",
      age:12
  }
}
//Valid
function returnSomething():x{
        let z:r ={
        name:"abc",
        age:12
    }
    return z
}
console.log(returnSomething())