A very common question asked with respect to Facebook Business pages is “What is the difference between Reach and Likes?”
The is simple the number of your fans that have clicked on the ‘Like button on your pages
From the Facebook blog…
If you haven’t logged onto Facebook in a while, your home page will default to this view.
Top News shows popular stories from your favorite friends and Pages, many of which have gained lots of attention since the last time you checked. In this view, you might find out about an old friend becoming engaged or see a hilarious video that your sister posted and that tons of your friends liked.
Since Top News is based on an algorithm, it uses factors such as how many friends are commenting on a post to aggregate content that you’ll find interesting. It displays stories based on their relevance, rather than in chronological order.