What's the difference between form button-link and js button-link?

What's the difference between these two ways to turn button into a link:

<form method="GET" action="example.com">                
<button type="submit">button text</button>
</form>

VS

<button onclick="location.href = 'example.com';">button text</button>

It has the same effect but is there any flaws of usage one of ways?