Instagram has made slight changes as to how to display Instagram photos on Facebook. Now, if you share your Instagram pictures on Facebook, your images will automatically be added to an “Instagram Photos” Facebook album visible to your Facebook friends.
And now, when you post your picture on Instagram, it will appear in Newsfeed on Facebook (in big format). On your Timeline, you can see a large format of your picture, together with your caption and the public URL.
Previously, as Instagram photos are not uploaded to Facebook album, there is no way to display a large picture. Now, since Instagram uploads the picture into the “Instagram Photos” Album, it can display the picture nicely.