Why does Google SERP for "www.domain.com" not also appear in "link:www.domain.com"?

Hi
Why is it that Google SERP that appear when you key in "www.domain.com" do not appear in "link:www.domain.com"

For eg.
www.toppopularstore.com returns 3000 results
http://www.google.com/search?hl=en&q=www.toppopularstore.com

whereas
link:www.toppopularstore.com returns 149 results
http://www.google.com/search?hl=en&q=link:www.toppopularstore.com&btnG=Search

Only 5% of the 3000 results (i.e. 149) appear as backlinks. Many sites that appear in the 3000 results do not appear as links in the 149 results. Is this because it takes time for them to be added as backlinks by Google? What is the difference?
Comments would be much appreciated.
Cheers!