We have ~600 articles in our Help Center and we want to one day leverage federated search. We're supporting a product so many terms are similar which is making it more difficult to find content best suited for the situation at hand with keyword search. 

Suggestion: Differentiate suggested search results by visibility setting: public vs. internal and differentiate external articles pulled in via federated search. Highlighting could be done with shading, colour-coded section/category titles, etc.