whats the difference between keywords in the answer and search priority words

Summary

whats the difference between keywords in the answer and search priority words as they both seem to be used in the search

Content

I have been looking at understanding the knowledge base with he view to hopefully improving our search function, An after read the documentation i was left wondering whats the difference between keywords in the answer and search priority words as they both seem to be used in the search function to find the relevant answer

Is their a subtilty i am missing ?