This is an interesting question, because on the surface, these two stories seem completely different from each other. The contrasts will be easier to find, so let's start there. For one, the narrators are different genders, in different time periods, with totally different issues. In "The Yellow Wallpaper" she is dealing with post-partum depression, and gets worse and worse throughout the story, completely breaking down at the end. The narrator in "Cathedral" is not suffering from a mental disorder, and achieves an emotional breakthrough at the end. The woman narrator is isolated from her friends and work, whereas the man is put into the company of new people and given a new experience to deal with. His socialization helps him, whereas her lack of it harms her greatly. In "Cathedral" the narrator starts off bitter and resentful towards his wife, and lets go and feels better as the story goes on. In "The Yellow Wallpaper," the narrator is not bitter at the beginning of the story, but gets worse and more resentful towards the end.
There are some similarities between these stories. Both narrators remain mostly unnamed throughout the story. Both of these characters have issues with their spouse on some level, and those issues impact their happiness. Both spouses put them in situations that they are not comfortable with, against their wills. At the end, both narrators reach mental breakthroughs and lapses from their normal perspective--the man in a positive way, the woman in a negative way. Both stories are written by the narrators, in first-person perspective. Both stories end before we learn the after-story of what happens to them. What are their lives like after their experiences? We are left hanging in both stories. Both stories address the capabilities of the mind, in either positive or negative ways.
I hope that those thoughts helped a bit; good luck!