When Natsu and Eiichiro are inside the tennis shop, in the manga, they are looking at the shoes while in the anime, they are looking at the rackets.
While Coach Aoi checks the things Eiichiro did in the past two days, in the manga, aside from what was included in the anime, Eiichiro also did something at 22:00 and 23:00. The anime actually reveals what Eiichiro did at 22:00 but it did not specify the time.
When the training has finished and Eiichiro is still has his weight training, Coach Aoi mentions this in the anime while in the manga, it is Coach Miura.
When Coach Aoi mentions that Eiichiro should go to America, in the manga, the background includes Barack Obama while in the anime, it is Abraham Lincoln.
At the airport, in the manga, only Eiichiro's mother is present while in the anime, Kageyama and Sasaki are present as well.
The scenes that are only included in the manga:
Natsu and Eiichiro's moments when Eiichiro is pondering what Natsu feels for him.
When Eiichiro is practicing his strokes with Coach Aoi, Coach Aoi makes Eiichiro to remember how Eiichiro hit the ball and its landing point to improve control.
Coach Aoi teaches the "between-the-legs" shot.
Coach Aoi mentions that Yuki Tajima also went to America for improving the tennis style. He only mentions of Takuma and Natsu in the anime.
Eiichiro asks permission to his parents regarding to the short-term study in Florida.
Eiichiro is starting to practice his English.
The scenes that are only included in the anime:
Coach Miura talks about the paperwork for Eiichiro's short-term study.
Eiichiro's day of departure is mentioned.
The classroom scene with Eiichiro, Kageyama, Sasaki and their other classmates. Eiichiro mentions that he will have a short-term study during their winter break so he cannot able to join them for New Year.
Eiichiro's practice on the day before his departure.
Eiichiro seeing Natsu on the day of her match (and the day of his departure) in order to cheer for her.
Eiichiro's flashbacks of people related to him (rivals, classmates, family) while inside the plane and checking of Natsu's message when he feels too much tension.