Question

Why it is said that girls are sensitive

Answer 1

Sensitivity - I don't know.
Emotional - mainly cos women (rather than girls) are more touchy-feely people while men are more simple and straightforward. Guys don't overthink as much as girls, hence with less thinking, they don't feel that much emotions other than those deemed necessary / spontaneous. E.g. Anger, frustration etc. Also, girls then to vent their problems with their girlfriends, which tend to be emotional problems (about boyfriend or the next hot dude in campus), as they vent, they feel more, such as relieved, happy. 

So, in sum, guys do less processing (in thought and emotion) hence less emotional. Girls think more feel more but lack clear cut action at times.

Answer 2

The emotions of men and women tend to be equal.but woman's are more honest about it.