I would think that as long as it has the same name, you get it.
So if you choose the assume supernatural ability (Breath Weapon) feat, you would get anything labeled breath weapon, but not if it's labeled something else in the entry. If the ability was for example called, Acid Breath Weapon, and you just chose breath weapon, you wouldn't get it. If it was called five breaths of Doom, you wouldn't get it.
With Eye Rays, or Manipulate Form, the abilities you get are rarer, but often better.