Facebook does not send all of your updates to all of your followers. For pages with large amounts of followers, only about 10% of your followers will have any given post pushed to their timeline. You can increase the number by paying FB to "promote" individual posts, but Twitter sends everyone everything.

For a commoner like me, FB only notify 10% of my friends. Is that the same thing for celebrities? It doesn't seem so.

I just take a sample using Justin Bieber's post that are both shared on FB and Twitter. On FB it has 385k likes, and Twitter only has 63k likes to the same content. The ratio is similar to MAU of the two platforms. FB is able to get more audience for him.

On Facebook people interacting with the content by liking and commenting will increase the content's reach by showing it to more people.

So it makes more sense for celebrities to directly broadcast to a larger audience on FB than Twitter...

Communication-wise, Twitter is a better platform for socialites and celebrities to connect with their audience. It's a one-to-many transmission model and one can send and receive as desired. It's model is more flexible and requires less maintenance for those who are busy or on the go.

Let's say you are a celebrity on the go, posting something on Facebook has a potential of reaching extra 1 Billion users. Of coz, there are more nosies with an extra billion users. However, you are still reaching more audiance than Twitter ...

I work in PR, here's my perspective: journalists love Twitter because they can easily share their articles and find interesting news shared by others (much better than Facebook bc you don't depend on a timeline, but rather on public hashtags and trending topics). Because journalists are there, celebrities are there. And because celebrities are there, journalists are there. It's a virtuous cycle. Twitter's also much easier to monitor than Facebook (private pages), so it feeds celebrity egos and the PR/advertising machine at the same time.

This really makes sense. Basically, Twitter is for journalists and celebrities, while Facebook is for commoners. No wonder why Twitter's user growth is pretty limited. The question becomes why it is hard for Facebook to adapt this hashtag and trending model? FB does have public profiles for celebrities.

You have to have a Facebook account to access Facebook content. I can read Twitter content without an account.

This is NOT true. Try log out Facebook, and you will still still be able to read public profiles of celebrities.

Facebook was created as friends network, while Twitter was created as followers network. Even though facebook added follow feature later, Twitter is still seen by many as followers network that suits celebrities.

IMHO In facebook, crazy users and annoying people can share longer rants and have bigger exposure. 140 characters cuts down the noise. Also twitter is already a replica of the star system: leaders and followers.

140 actually makes average users hard to understand what does it mean without context information. This is also the reason that Twitter user number stops growing, even slower than the gigantic Facebook.