I've talked about this before, but more in passing. In sports series, I see two main aims that a character (a "good" character, that is) can have: "enjoy your youth" or "aim for the world".
"Enjoy your youth" means that while you're in school, you'll do your best in your sport so that when you move on to adult pursuits, you won't have any regrets about that stage of your life. Some characters take up the sport for this very reason, to experience that part of school life. There's usually no expectation to continue in the sport beyond high school, or perhaps university.
Kawamura is a good example of "enjoy your youth". And in general, teams in series where the main goal is to go to/win at Nationals have this as their motivation.
"Aim for the world" means that you want to be a pro, your sport is what you want to do with your life. (Presuming you have the skills, of course. And with the realization that you will have to retire at some point.) School teams and competitions are valuable, but if they hold you back, you'll have to move on. It's a more personal journey and it's a harder one.
Rukawa (Slam Dunk) is a good example of "aim for the world".
Of course, series often contain elements of both: players on the same team have different aims, the focus can shift part-way through, etc.
And this seems like one of the big differences between the Prince of Tennis manga and anime. For Tezuka and Ryoma, the manga is much more "enjoy your youth" and the anime is "aim for the world".
Today I was thinking about Seigaku as an elevator school (in the context of reunion stories, actually, but that's beside the point). And it pinged me: in the manga, when Tezuka goes to Kyuushuu, he's at the hospital for the Seishun university. Not only does he stay within the same country, he's still in Seishun. He's still inside, still part of the system. Still in the school.
When we see him face challenges there, he goes up against a rival school, one that he may face later at Nationals.
In the anime, he goes to Germany, to a sports clinic that has treated players from all over the world. He's out of the country and out of the school, moving into a international sports environment. When he hears about it, Inoue remarks that Tezuka can travel all over the EU and see the tennis there as well. It's a good opportunity for him.
There, his project is his trainer, a former pro, who has stopped playing.
In the manga, I don't get a strong sense that Tezuka will become a pro, even if his arm will allow it. If he stopped playing tennis after high school, I wouldn't be surprised. In fact, if he stopped after junior high, I wouldn't find it totally out of character, especially if they do meet their goal. (Though -- wasn't the goal to go to Nationals? Which they've now done.) Enjoy your youth, Tezuka! (If you're not middle-aged already.)
In the anime, I think that so long as his injury or other responsibilities don't prevent him, Tezuka will at least make the attempt to go pro. It seems like his family could afford to support him while he tries. Aim for the world, Tezuka!
And Ryoma. In the manga, well, he stays put. He plays with the team, he goes on to Nationals with them. Not to say he's not expected to move beyond that and become a pro, but for now, he's there as part of the team.
In the anime, he gets a first taste of international play with the American Goodwill games arc. This isn't a school team, it's a national team (well, more regional). And then, he leaves. Leaves Seigaku, leaves Japan to go play in the US Open. OVAs notwithstanding, this is really his transition into the pro world.
It's not quite the same as with Tezuka, but it has the same flavour.
So, in conclusion, I am wearing a shirt.