Google reports different number of links with link:www.site.com and link: www.site.com and links: www.site.com commands. What is the intended difference between these commands?
link:www.yoursite.com returns the number of backlinks to that site. Link: www.yoursite.com and Links: www.yoursite.com does only return resutls that has the word "link" or "links" + www.yoursite.com in them.
Correct. Think of it this way: without the space, you are using the syntax for a Google "special" search feature. If you add the space, Google sees is as two separate words and will then search for pages that contain those two words -- you have stopped using the special search syntax and gone to regular search.