Both are manhwa shoujo, which involve "jjangs", gangs and romance. Quite similar twists/developments - the female lead is kidnapped as part of a revenge plot, etc... Although the female lead from He Dedicated to Roses cross dresses as a guy for parts of the story. Both female leads are treated similarly by their classmates (in Hana Yori Dango it's due to Makino's social status, while for Ida it's because of her maid-master relationship with Mimi in HD2R).
Both the protagonists are female and the leader of a fighting time (even though Han-ah has no choice), they b oth get stuck in love predicerments and the back stabbing 'best friends' who tries to ruin there lives.
FIghting scenes, love devotion and Cutie boy is all straight love.
Both are well thought out and Hard to put down =)
Personally, I like He's Dedicated to Roses way better than this Cutie Boy. Cutie Boy's characters were really just too dumb and helpess for me. Almost to the point where I coulodn't stand it anymore. He's Dedicated to Roses isn't that far of a step up (as both of the leads are dumb or helpeless as well), but for some reason I just find myself liking He's Dedicated to Roses much more. There are a lot more bishies in that one too. <3 Both are worth a read though. If you like one, you'll have no problem with the other.
Similarities: Both manhwa, both great art, cute shoujo romance style, both involve jjangs/gangs and all that fun stuff, female lead doesn't have complete control over her life, etc. etc. read more
The female leads are similar as they are pressured by their peers (at different levels of severity), they get called average by those surrounding them (looks, grades, etc) and share similar love interests. Yoo-Min and Tsukasa both bully the girls they love without realizing the troubles they're causing and are leaders of groups which are notorious within their area. There are also some similar plots, such as the female lead being kidnapped in a revenge plot against the male lead then get saved by the male lead.
Both are manhwas about a girl who starts a relationship with the "Jjang" of a high school. Quite similar twists/developments - rivalry between two jjangs over the female lead, the female lead is kidnapped as part of a revenge plot, etc...
Both have a female lead that was tormented by the male lead as children. Their emotional and psychological scars carry into the future making it difficult for the male to form a romantic relationship with the female. Although, Cutie boy is set in high school and has a more comedic tone than Kimi no sei, which so far seems to have a more mature feel to it and it takes place while the main characters are supposedly in college.
In both a tom boyish tough girl gets involved with a gang which is the exact kind of people she hates the most!! She has to stay by the gang leader's side because either she has to pay off a huge debt (tokyo crazy paradise) or has to become the girlfriend of the gang leader (Cutie Boy) but as she gets to know the gang leader she finds out that he's not so bad, when he's not annoying her!!! Both of these series are really good :)