Xayah and Arcane Comet/Manaflow band

Question about if this is intended or not. Arcane Comet procs Xayah's passive, however Manaflow band does not proc Xayah's passive.

Is this intended. I feel that they're basically the same exact ability with how they're written so Xayah's passive should proc both or neither but not one or the other. Arcane comet says "Damaging a champion with an ability hurls a comet..." and Manaflow band says "Hitting an enemy champion with an ability..."

The only thing that differs is "damaging" from both of those conditions. However Xayah's passive is considered an ability, and it does damage so arcane comet will trigger. Then Xayah's passive is considered an ability and it hits an enemy champion but does not trigger.