Movie and musical, Newsies is fairly similar from screen to stage. There’s a scene with a different setting here, a cut character there, all the typical adaptation adjustments. This makes a lot of sense when you consider that the original was a movie musical to begin with, created by the same company that created the musical.
But if you’ve seen both versions, you’ll know that there is one very big way that the stage show differs from the movie.
The Love Interest.
I say “Love Interest” instead of calling her by name, because her name differs depending on which version you’re watching. In Newsies (1992) the love interest for protagonist Jack is Sarah Jacobs, the sister of newcomer newsies David and Les. In Newsies the musical, Jack’s love interest is Katharine Plumber, a reporter eager for a chance to prove herself that takes on the task of reporting about the newsie strike.
This isn’t a case of a character with a slightly different situation or name. Katharine and Sarah are completely different characters, with different relationships with Jack. Sarah’s romance is more traditional, whereas Katharine and Jack have a more, say we shall, bickering kind of romance. (For a better idea of what I mean by this, see Katharine’s song “Watch What Happens” where she calls Jack “heroically charismatic” and a “cocky little son of a-“ within about two lines of each other.)
The impact on the plot is also drastically different between the two characters. Sarah’s impact on the plot is very little. Her main connection to the rest of the story outside of her romance with Jack is simply through being the sister of two more major characters. Katherine’s influence is greater, in part because Katharine isn’t just replacing Sarah- she’s replacing Bryan Denton, a male reporter that covered the newsie strike in the movie.
This change gives Katharine more agency, as she now has the motivation of wanting to prove herself in a male dominated field. (This also happens to tie in with the themes of the newsies’ story-they want to be taken seriously by grown men that dismiss them despite the work they do and seek to take advantage of them, and Katharine wants- well, the same thing.) Whereas Sarah could be written out without changing anything besides Jack and the Jacobs brothers, Katharine now plays a crucial role in the story, and with her need to prove herself, fits the role more meaningfully than Denton did. (And the story does more to make Katharine crucial to the story, but that gets into more definite spoilers.)
Overall, by changing the love interest, Newsies the musical cuts down the amount of named characters while making the ones they have more emotionally important. It makes the romance more compelling by giving us two characters that exist completely outside of it, but it also makes the musical as a whole stronger.