Those are the emoji sets that are shipped with the latest version of the forum software. They are usually browser-based, so their looks depend on what browser you are using. Here at JREF, we use the
EmojiOne set.
This page illustrates all possible variations of a particular emoji:
A yellow face with simple, open eyes and a broad, open smile, showing upper teeth and tongue on some platforms. Often conveys general pleasure and good cheer or...