Aside from photo technology and clothes, there's hair and facial hair styles which make a big difference. Look at people from the 80s compared to now in color photographs for examples.

People aged differently "back then" too. If you look at people in their 20s from many decades ago, possibly particularly during war eras, peopled seemed to just age faster. Soldiers in photos look nothing like baby-face soldiers from the modern era (when I was enlisted).