I'm glade someone is intelligent to state the obvious.
For guys that are circumcised, their penis tip is constantly rubbed (undies), which causes it to loose sensitivity. guys that are circumcised have less chance of getting infection.
Guys that are not are more sensitive, have a greater risk of getting infection (mainly as teenagers because they won’t clean thoroughly) (they need to pull back the foreskin and wash). Though if they are taught properly how to clean and why, it means less hassles later on.
When they are erect they all look the same.
And yes I do know what I am talking about I was a professional nanny for many years (not an any girl, but a qualified highly experienced)