What is the difference in the Content Brief numbers for important terms and the recommendations for the same terms in the Variations and LSI tab?

There are times when you need to make judgment calls in SEO. The Content Brief makes those judgment calls for you. It's like having a high level SEO looking over your shoulder. The Variations and LSI tab simply gives you your current usage and your competitor average. The Content Brief then makes recommendations on what you should do with that information and how to apply those recommendations to your target page.