People who are highly intelligent tend to have a sloppy handwriting, so if you can't read a note from your colleague or a random person you just met, don't judge them too closely.
As someone who is not as young as he used to be, I can certainly say that I find youngsters and youths confusing, not in terms of the meaning of the words, but in terms of their lifestyles.
作为一个已不再年轻人,我得说我真是看不懂年轻人(youngsters and youths)了,倒不是说不懂这两个词字面意思,而是他们生活方式。