Favoriting something with a star is a big commitment, you know? We just don’t know if we can commit to making something our favorite. And the smiley faces for Vine? It’s just too much And that’s what we’ve had to do with Twitter and Vine, which featured star symbols as a “favorite” and smileys for “likes.”
Twitter felt that the star was a strange symbol to newcomers, and the heart would be a more recognizable symbol for liking something. That’s fair, though it seems like a very insignificant change. Either way, you’ll start seeing it across all applications on all platforms, including Twitter for Android, Vine on Android, and the web.