"Why does even people compare Facebook and Twitter?" Both of them have something in common and that's why critiques start comparing them. Facebook was created by Mark Zuckerberg in 2004 while Twitter was launched by Jack Dorsey in 2006. They are both emerging start-ups this decade. Facebook and Twitter are also popular social platforms that have managed to attract millions of users in a short period of time. Besides having a high daily return rate from the duos, they also succeed to out-compete their close substitutes in United States and became winner-take-all giants.
However, they are only common in backgrounds, lying on the the similar growing path, showing the same promising trajectories in the future, they are really two distinct types of social platforms in terms of the natures and functionalities.
Twitter is a micro blog, which is mainly text-based while photos and videos are just some minor ingredients. On the other hand, Facebook is a multi-media platform that connects online persona, where users can play games, share photos and videos, write notes, and share all kind of personal information and statuses.
Facebook and Twitter both broadcast the users's statuses with a diversified openness and closeness. Twitter is open to public, where users can follow whoever they have interests in and they can read every public twit. On top of it, the openness also allows Twitter to turn itself into a large discussion forum when there are hot issues. In other words, Twitter is a real time search engine for the thoughts and comments from people all over the globe. In contrast, the friends on our Facebook are mostly people that we have met while we might follow people that don't even know us on Twitter. Facebook is more restricted and closed. By default, people, who aren't our friends, can't access to our albums and our walls posts, while they can only view our profile pictures and some personal information. It is also this restriction that allows the users to be protected (besides the privacy issue). Simultaneously, it is also the closeness that encourages the users to share his/her personal issues with all his/her group of friends. Although Twitter permits users to set some twits to be private (allowing only the followers to read), users don't have as much control as they have in Facebook, where it enforces the permission process to follow a friend.
Facebook and Twitter have many other disjoint properties, such as Twitter is more popular in North America, while Facebook is being accepted by more countries. It is never enough to discuss all of them. Before my last comment, I want to ask the readers two questions, " If you are a regular Facebook users, how would feel if you find Facebook is overloaded with instant text updates, if you find your wall posts, photos and videos are going public (no permission needed)?" "If you are a daily Twitter user, what is your reaction when there isn't a 140 length limit per twit any more, will you be overloaded by the amount of text that people are typing over the whole user network? What is your reaction if Twitter enforces permission before you can follow someone? "
Facebook and Twitter are functionally differentiated, thus they serve different purposes from the perspective of the users. As long as the nature of both giants are unchanged, I couldn't see why one would replace the others. After all, user demand drives supply, isn't it?