The Ultimate Physicist and Ultimate Botanist titles were slightly different in the first game.
On the Danganronpa Wiki, you’ll see that in Japanese the Ultimate Physicist’s title is written as 超高校級の「物理学者」 and the Ultimate Botanist’s title is written as 超高校級の「植物学者」. What’s interesting is that you would expect their titles to be written that way in the original game, but it’s slightly different.
When Monokuma talks about the Ultimate Physicist, their title is written as this:
And when Monokuma talks about the Ultimate Botanist, his title is written as this:
In both of their titles, 学 is replaced with the highlighted kanji. Thanks to @blackflirtlarping, she translated the top image as “physics researcher”, so the title is Ultimate Physics Researcher. She also says that the change from “physics researcher” to “physicist” isn’t very significant since the meaning of the two titles are almost the same. (This all can also be apply to the botanist title.)
As to when the title change has happened, the earliest I found is the Danganronpa Visual Fanbook (February 03, 2011). In it, it talks about Santa and says his talent:
While the image is blurry, it looks like it says 植物学者, which is what his title (Botanist) is written as now. And if his title has been changed at this point, it’s possible that the same thing happened for the Ultimate Physicist’s title.
This is a pretty early change since the Fanbook was released under 3 months after the game was first released on PSP (November 25, 2010). As far as I’m aware, there hasn’t been an official reason given for why the titles had changed. My theory is that they change the titles because calling them a scientist sounded cooler than calling them a researcher and, as blackflirtlarping said, the titles would almost be the same anyway so it wouldn’t be a huge change.
