Hello Adee
I believe the two pictures are of the same person but the first,I suspect is slightly earlier than you suggest.
The one thing that remains constant throughout life is the shape of the ears, which in this case appear very much the same. The style of painting doesn't look right for the period in the first picture - could it perhaps be a coloured photograph? whatever it is, I think the gentleman is nearer to his 30's than 40's.
I'll leave it to others to prove me wrong, but I think it's the same man.
Regards
AJ