I'm referring to when they first met. Ada being friendly and saying hi, then defending her from the kiss ass noble girl, even buying the crystal ball for her in a gesture of goodwill. Kaye decides they are both snobbish nobles even though Ada didn't do anything or say anything negative to her.
Caroline in comparison also defends Kaye from their bully commoner roomates and she decides this time to try and be friends.
What is different? Both were nice and friendly, both helped her deal with bullies, added bonus to Ada for trying to protect Kaye from the crystal ball that overloaded from magic.
What exactly has Ada done or said, aside from one instance of recoiling in shock from hearing 'Demon Lord', that justifies Kaye's animosity?
Have you reread those chapters recently? I ask since there's a reason for the difference in her response and I'm assuming the disagreement is because it's just been a while but correct me if I'm wrong.
Kaye meets Ada first when they both are trying to buy the same orb, the last orb of that type. Ada's eventual friend then arrives and flaunts her money, making fun of Kaye (and Ada) for being poor (she mistakenly thinks Ada is poor then). Kaye is immediately taken back and put in a bad mood. This whole scene happens after Kaye had just talked with her father, when she learned how hard he works as a poorer person and how poor their living conditions were.
After the rich girl mocks them, Ada reveals that she too is actually rich and decides to "flaunt" her money by buying the orb away from that rich friend. Ada does not mean to flaunt but doesn't realize how what she's doing might look like to Kaye and Kaye is not a mind reader. Ada then decides to "gift" this purchase to Kaye to annoy the friend (but likely also to be nice).
Kaye sees this as two rich girls arguing by using their wealth and the gift, she sees as a pity hand out and more as an attempt of Ada to stick it to her friend. She says something like "I'll earn this myself," and makes a comment about the spoiled rich class. She feels like they both used her as a pawn with disingenuous "help" using their overwhelming money that they are free to just casually throw away.
Ada then becomes friends with this rude, rich girl and Kaye sees them together later, likely reinforcing her opinions about Ada's real intentions. She's wrong, but it makes sense from her perspective. It's not about hating nobles, it's about hating overbearing (and rude) "richness" and that's something even a Japanese girl could very well carry with her (especially if she's read these stories and assumes how these people will behave).
All this to say that her introduction to Ada was not the same as Caroline and she got off on a bad foot with Ada for reasonable reasons. That bad introduction then colors how she views Ada for a bit. Caroline has had no such bad introduction.
