format question

[musicus]

I'm a bit confused about the difference between format for score versus part.
I've always figured that the score pages should be longer vertically than a part.
On the attached, I used Page format/score A4, File menu (same), Redefine pages /all.
But for a score page, I used the exact same settings. On the attachment (Aria - bassoon),
the overall size of the page looks like a legal size. Shouldn't I make the settings for this part
look more like a letter-sized page rather than legal size? (In both cases they are going into pdf.)