If you can buy the gun on the top, but can't buy the bottom gun, who cares? You still have a gun.
UPDATE: Megan McArdle responded to this post at The Daily Beast. She writes, "I'd turn that question around: if it makes no difference, then why have the law? "
UPDATE2: Media Matters says that these guns are very different. And, for the record, I didn't create this image. I found it on Facebook. I have no idea where it originated.