http://www.whitehouse.gov/sites/default/files/rss_viewer/birth-certificate-long-form.pdf

So I guess there's a perfectly good reason why Snopes would have cropped the document posted on whitehouse.gov ?  They wouldn't have any motivation to hide the fact that the security paper background is obviously not original and exists as a separate layer?

Go ahead and compare them.  The evidence is right there, plain as day.