Okay, so here we have a seemingly minor Facebook design change that could be of no significance whatsoever BUT what have we learned about tech companies by now? Follow the money!
Facebook has made a change to how you interact with stories you see on third party websites that have Facebook functionality as well as stories you see within Facebook apps. It used to be you could "like" a story OR "share" a story. Now the "share" button is going away and when you "like" something, that story summary appears in your feed (and the feeds of all your friends). It is expected that this same thing will come to the feed itself soon. So instead of just innocently stating that you enjoy something, you will in effect be republishing it.
The Money - this leads to more linking out to third party sites, of course. But Facebook will use what's called a "ref tag" that lets those sites know that Facebook sent you there. Then if you buy anything or click on an ad, Facebook gets a cut.
At the same time, of course, you're sharing more. And Facebook always wants that.