While we're on the subject, can somebody explain the behavioral difference between a star (or heart, whatever) and a retweet? They seem to have nearly the exact same effect
Using Facebook for comparison, a retweet is similar to the 'share' button. Heart parallels the 'like' button. Retweeting explicitly draws your followers' attention to the tweet. While a heart seems to have a multitude of purposes: right from expressing sentiment to bookmarking. Twitter in this case wishes to make it clear to new users that Heart is how they express sentiment. Behaviorally, retweets tend to be expression of public endorsement. While hearts(previously favorites) are a semi-private invocation of approval or interest
A retweet means the tweet being retweeted will show up on the feed of people who are following you. Star/Favoriting is just like a personal bookmark. It won't automatically show up on followers feeds.
They do also show your favourites in your followers feeds at times. I see it quite frequently. Retweets always show up to your followers. Favourites sometimes do. I don't know how they decide to show them in the main feed.
A retweet puts the tweet into your public feed, as if you had tweeted it (of course, in the UI it is correctly attributed to the original author). A favorite/star/heart/like/"the other button", just flags the tweet in your account so that you can refer to it easier later (in another, less public feed).