Meninos Antes de Flores (2009)

They are similar because:
Similar theme: Both set in school/university + flower boy concept
There's a love triangle between the female and male lead and one of the 2nd male leads
4 male leads who are popular in the school/university
The male lead hates the female lead and there is some bullying and then they fall in love
Rich boy poor girl type of drama

Differences:
None of the male leads knew each other before becoming roommates in Hi Flower
More business/company feud in Hi Flower
The female lead is an orphan and struggles to support her and her brother's education.

Both dramas look at class difference. Both have working class FL and rich ML. In both the ML is anti social and rude. Both have the FL going through bullying but not as excessive as Boys Over Flowers. I loved the vibe of School 2017, the friendship is shown really well and seems more relatable.

Miyu and Shuya are high school students. They have dated for 2 years. Miyu and Shuya have a promise that no matter what, they will watch a movie together on the first day of each new month. When Miyu and Shuya are on their way to the movie theater, Shuya suddenly cancels their date. Shuya seems like he is hiding something and he acts nervous. Later, Miyu goes to the place where she is supposed to meet Shuya, but she witnesses Shuya getting into a car accident. She panics, but when she wakes up she finds herself on the morning of the accident. Miyu keeps waking up on the day when Shuya got into an accident.

They both have the Flower boy concept. In the case of BOF its F4, while in AGD it's F40.

they give off the same vibe. the two main girls remind me of each other. the two main guys are jerks to the girl the majority of the drama.

They are both romantic comedies with very sympathetic female leads who have to go through a lot of hardships to achieve their dreams. 30b17 is much lighter and is more comedic in tone and though the main male lead is also not very nice to the female lead at first, it was more coldness than the bullying that occurred in BOF. Both have great looking swoony male leads who start out as harsh and cold and eventually warm up due to the lovable and plucky female leads. Both have very caring second male leads who are always there for the female lead characters and were basically her first friends in the new world she found herself in. Both first and second male leads have very close relationships that get tested because they fell in love with the same girl though in BOF they both knew of their rivalry, in 30b17 only one guy knew that he was in a love triangle but both second leads had a moment of having to choose between their love for the girl or the guy.

Both involve a rich guy and a poor girl. The guys mother disapproves and does everything she can to break them up. There is an attractive supporting male who catches the lead females attention and causes her to question her relationship with the main rich guy. The main guy learns how to act like a decent human being thanks to the main girl.

Small things like that.

BOF has one main girl and 4 hot guys. (Gu Jun Pyo from BOF and Fang Ting Hao from TWG are sooo hot)... anyway you should really give this drama a try!!!