The search keywords field is to help readers find your eBook when they don't already know about it. (ebformat.com)
If your book is in one of these categories you need to enter at least one required keyword in the KDP keyword field for your book to appear in your intended category. (authorimprints.com)
Amazon's Kindle keyword field in KDP is one of the main reasons why I advocate distributing your eBook via KDP rather than through a third - party distributor. (authorimprints.com)