While not really the best out of the Thai's, there are similar treads of coming of age, leadership, swimming, and friendship.
The differences come where the Thai story is, of course, a BL
Both dramas are about high school boys who are looked down upon one way or another, and are eventually involved in a water sports team that they establish at their schools.
Yamada Takayuki is in both of the drama's as the main character, while H2 were about Baseball team, Water Boys were dealing of the problem in Men sychro team.
A group of misfits join a school club by chance, become friends, and little by little serious about it. A typical underdog story about friendship/love, acceptance and hard work.
Not much in common, but definitely check «Beach Boys» if you liked the bromance of this show and vice versa, «Water Boys» is a must-watch if you like bromance. Both are healing summer shows, and classics
They have a similar concept of young boys competing in a sport, water boys synchronized swimming and tumbling with rhythmic gymnastics. It was during high school, through the sport they learn to build their friendship and love the sport.
They both have high school young men, and all the members learning a sport, the only difference is that water boys didn't have delinquents. Rookies were a bunch of bullies, thugs, outcast brought together to play baseball.