I would appreciate any opinions regarding whether the subject in the two photos are the same person
Here is a link that might be useful: Benjamin F Stone
none of the links nor the URL's you posted work.
Here is a link that might be useful:
The links are updated and should work. Sorry about any inconvenience.
Hard to tell features with such tiny pictures (and the portrait is not a good imagae) but, from the clothing style of the portrait I'd say late 1830s- here's a similar dated image from 1838 with an almost identical hairstyle, cravat and coat style:
If the potrait was painted in the 1830s, as the two men appear to be of a similar age it's unlikely they are the same person, as photography wasn't around then.
The man in the photgraph appears to be wearing a sack suit and ribbon tie as were popular in the 1880s.
The man in the portrait seems to have a shorter, broader face with a squarer jaw and quite dark hair and brows compared to the man in the photograph. Without better images it is almost impossible to see if there is any family resemblance, but I would say definitely not the same person.