Top search queries lists the top 20 searches in which your site appears (impressions), while Top clicked queries shows which queries generated the most clicks (traffic).
Review the first list for expected keywords. If keywords you expect to see don't appear, your site may not have enough useful content relevant to those keywords. For information about creating rich, user-friendly sites, check our webmaster guidelines.
Make sure you're not accidentally blocking Googlebot from crawling pages on your site.Check your robots.txt to make sure it's working as you expect.
Compare the first and second lists to identify how you can improve your content. There are several steps you can take to make your content appear more compelling so that users click your site in search results pages. Your page title appears in the results, so make sure it's relevant and accurate. Google can display the text in your pages' meta descriptions in search results, so review your meta descriptions to make sure that they contain useful descriptions of your pages' contents. Information about changing titles and meta descriptions.
If you have an AdWords account, review the first list for ideas for AdWordskeywords.