First, except for Obama, the first picture is a nicely choreographed headshot (make up?) and the second is a candid photo with no attempt to make the person look good.

Second, except for Bush'88, all of those Presidents were in office for 8 years. I don't know about you, but I'm not surprised a person in their later years looks older almost a decade later.

My Mom was never President, but she looks much older when she was 60 vs. 52.