What makes this cool? This was Jack's exact birth weight and length. What else? Henry was 4 days early and Jack was 11 days late so Henry weighs what he would have weighed had he been born 10 days past his due date.
What's the difference? Head size. Jack's head was always in the 90th/95th percentile... while Henry sits comfortably at the 60th. So if you think they look alike but can't figure out what the difference is... perhaps that is it.