Is sharing the same as liking?

They are similar, but not exactly the same.
Sharing gives the user a chance to add an extra comment that appears with the content on their timeline. It also lets them choose to share with only certain groups. Liking doesn’t give the user those options.
However, the end result is that the item shows up on the user’s timeline/news feed in pretty much the same way.

Facebook has more information in their help pages, starting here: https://www.facebook.com/help/216373778387917

on your fb counter, is it displaying the number from likes, shares or aggregating both?

thanks

I’m pretty sure it is just the number of shares, and doesn’t include likes. Their graph API gives access to both, but it now requires authentication so the plugin no longer uses it. The API that the plugin uses now only returns a share count value.

Cheers,
Sarah