Why Does Changing InnerText Value Also Changes InnerHTML?

I have a asp.net code that creates a button as follows:

So for example, if you did this:

var div = document.createElement('DIV');
div.innerText = '<span>Hello</span>';
document.body.appendChild(div);

Then you'd actually see the string "<span>Hello</span>" on the screen, as opposed to "Hello" (inside a span).

There are some other subtleties to innerText as well, which are covered in the MDN article referenced above.