Q: Website XML Sitemap - are the xsi and schema portions needed? and differences?

For the sitemap xml of my website, I noticed that different articles suggest different things..

For example, prior to my page listings, some articles suggest starting it this way:
<urlset xmlns="http://ift.tt/xwbjRF" xmlns:xsi="http://ift.tt/ra1lAU" xsi:schemaLocation="http://ift.tt/xwbjRF http://ift.tt/Av6BHN">

While other articles have it layed out using only:
<urlset xmlns="http://ift.tt/xwbjRF"

So my question is, do I need to include all of the extra stuff from the first example?
And what exactly is the difference between using the extra parts, or not using them?

Thanks in advance!