I took a look at the guitar tab for both songs, and was actually surprised at how different they were.
Make no mistake, though, they are still almost identical. "Someday" is in dropped-D tuning and "How you Remind Me" is not and therefore the tablature is laid out slightly different, but they play almost the exact same successive harmony throughout the entire tune.
And it also comes to bear that every single break, chorus, fill, and solo happen in perfect sync to each other. It's as if they took the first song's complete tablature, erased a couple 5's and 7's, replaced them with 7's and 9's respectively, and wrote "Drop D" at the top.