Guys never notice differences in their friend's appearance unless the difference is too obvious (like a very poor haircut that leaves the scalp like a partially mowed lawn). But with girls, it's not the case... Try walking to your friend who is a girl (the phrase girl friend avoided for obvious reasons) with a small stain on your shirt which is usually unnoticeable. Chances are that you would get caught within the first couple of minutes.
Guys try their best to be caring but come on... they are not designed for that! Girls often tend to care more than what you want them to and often that makes them question every 10-15 seconds about your wellness. If you are down with fever and you let your best friend who is a girl (quite funny to type) know, chances are that you'll end up answering the phone at least 20 times that day!
Almost everyone has some childishness in him/her. The famous quote "There is no point growing up if you cannot be a child at times" is an illustration of that fact. However, the proportion of girls I've observed to be childish is much higher than what I observed in guys!
Even the most silent girl is highly talkative within her group. With guys a reserved guy is a reserved guy wherever he is but with girls, a reserved girl acts differently when she is with and when she is in a larger gang.
I might be generalizing a bit too much here. But many girls are possessive about their friends and belongings! At least that is my observation.
A girl who stays at home knows much more than a guy who is hanging out most of the day!
Girls seem to depend on someone way too much either emotionally or personally but at the same time they easily switch preferences. Someone who was inevitable a couple of years back becomes a good friend today and a good contact tomorrow. At any point, a person who shows a lot of interest on her is always considered the best by a girl! Again, may be I'm generalizing... But that's something I observed out of my experiences.
With the brain being locked in an emotional trap, girls usually end up taking decisions purely out of their heart which in most cases will not be correct. Ironically, even after realizing that they made a mistake, it is next to impossible for them to correct that.
Hypocrisy when it comes to guys:
Girls enjoy guys falling for them but many do not want to reveal that. A beautiful girl almost always confirms that the guys around her are interested in her through unnoticeable gestures. Guys however strong just start shaking at the sight of a beautiful girl staring at them and get caught. But a girl never reveals anything more than a smile at the corner of her lips... Gets hard for the guys to assess her pulse