Thanks for pointing this out. I went back in and checked and I was using the -progressive option on the jpegtran command and so the comparison was done with -progressive.
However, when I generated the image in the blog post I didn't do that and so I have rerun it. Updating the blog post now.
However, when I generated the image in the blog post I didn't do that and so I have rerun it. Updating the blog post now.