Personally, I think there need to be more than just two divisions - nice guys vs. jerks. Let me break it down some more:
(By the way, I don't like making social groups like these. Anyone probably has a number of different traits from each of these categories, but
in general these categories are pretty accurate.)
True Nice Guys - these guys are a pleasure to be around. They control their anger, they're polite, they talk very highly of you and many others...ie they make you feel happy. They're not aggressive and sometimes a bit passive, but their passiveness doesn't seem to bother them - they just accept it.
I know a guy like this. He is the happiest and nicest guy I've ever known. He's not very sexually masculine, meaning he doesn't give out a vibe of being much of a man or a big success with the ladies, just a decent person. He has a girlfriend, though.
Nice Guys With a Chip On Their Shoulder (Bitter Doormats) - these guys could have originally been like the one I described above, but they eventually started to feel dissatisfied with themselves. Most were not like that, I believe. They've always been passive and non-offending, but the major thing is that they're pissed at girls for not wanting them. In one word - they're bitter. They get frustrated very easily (we all gret frustrated sometimes, but these guys keep that frustration and let it build up, making them more annoyed as time progresses). A lot of times as well, they try too hard.
I knew a guy like this also. Towards the end of my freshmen year of college I started to go out to parties a bit more often with the people in my dorm. Some nights I managed to get a girl's number or hook up with one and some nights were completely dry for me. It didn't bug me and I would just try my best to enjoy myself if no girls seemed into me on a particular night. This guy, however, would go out with the intention of getting laid and would leave the party early every time, annoyed and disappointed. I wasn't any don juan myself obviously, but I thought that maybe I could talk to him and we could help each other out. After talking with him, this guy was very bitter towards girls that it was disgusting.
Fake Nice Guys - they are very similar to the guys with chips on their shoulders, except these guys might not be so genuinely decent. Instead, they have the false idea that the way to get girls in bed is to smother them and be overly nice. Then when this doesn't work (and when does it ever work?) they flip out, become extremely frustrated, and become bitter.
With the guys I talked about above, they're at least being themselves, but are becoming bitter over the fact that no girl seems to be attracted to who they truly are. Fake nice guys aren't even true to themselves - they pretend, and tthey have very bad choice in what pretending to be.
Wannabe Jerks/Players - these guys are the most pathetic. They're not a pleasure for any decent guy to be around, because sooner or later they'll start ripping on the decent guy to impress a girl. That's their thing - they're insecure with themselves that they have to belittle other guys. They do most things to look hot for girls - tight a&f clothing, earrings, very define body, etc. The only thing they have going for them are their bodies, which do attract a number of girls, but their whole mind is based around their body. Sometimes at parties, I'd be talking with a girl and one of these guys would interrupt and make fun of my pecs or arms and tell the girl to feel his.
Or I'd just be walking by, and they'd bring me into the conversation as a stepping stool for their egos.
Bottom line is, they appear to have confidence to some girls, but that fake confidence comes from being a jerk to other guys and their fitness alone - not their brains, personality, etc.
These guys can succeed with dumb girls who can't tell the difference between confidence and fake confidence.
Real Jerks/Players - these guys just don't give a ****. As a guy, I can usually tell the difference between a real jerk and a fake jerk, and let me tell you, I have a lot more respect for a real jerk. Most of the time I find them to be funny and entertaining and end up liking them a lot.
They're "jerks" in the sense that they'll say anything with tons of confidence and they won't care what other people say/think in response. They might make a crack at you, but they won't harp on you like fake jerks will. They don't do it to boost their ego - they just do it because that's they're personality, to be a wise ass. They don't need to resort to belittling other guys to impress girls, because they have plenty to impress them with already.
A guy I knew was just like this. A bit shorter than me, but very muscular. He would say the raunchiest stuff with such boldness that guys couldn't help but laugh. Granted, he put off and offended a lot of girls, but his utter manliness and
I don't give a **** attitude seemed to attract so many more.
Gentlemen - the right balance between jerks and nice guys. These guys won't be offending like jerks will, but at the same time they don't take **** from anyone. They'll have more tolerance than jerks - ie they are better at controlling themselves and keeping cool in situations where people are showing them disrespect. Unlike jerks, they don't resort to getting macho and physical when someone shows them disrespect - they're cool and charismatic enough to brush it off with words and a good smile. Gentleman don't bash other guys, period. They don't need the ego boost and it's not their personality.
I think the best way to describe a gentleman is a cooler and classier version of jerk. He has the same amount of confidence, but is less controversial or noticeable. Think of it this way - a girl walks into a party and the first guy she notices is the vin diesel-looking guy who has his arms around two girls, is loud, and is the dominant voice out of the circle of people he's talking to. He'll turn heads a lot and will get a mixed variety of reactions.
She might not notice that cute and classy gentleman, smiling and talking to maybe one girl or one of his friends or two. Depending on what the girl who just walked in likes, she might stick around the jerk the entire party, or she might go to the jerk to begin with, but then notice the gentleman and slowly gravitate towards him.
The gentleman is more subtle than the jerk or player, but he is not any less masculine or confident. It is simply a different style.