The difference between Facebook and Twitter is perfectly summed up 1 line in a job listing

Facebook and Twitter were born only two years apart.

But the two social networks have had very different lives. Facebook now has more than 1.6 billion monthly users, and continues to grow. Whereas Twitter's growth has topped out at roughly 300 million users.

Facebook cofounder Mark Zuckerberg has led the company and called the shots from day one. Twitter has had a succession of CEO changes and internal turmoil, with cofounder Jack Dorsey currently doing his second tour of duty as CEO.

The two companies also have very different internal cultures.

At Facebook, one of the mottoes celebrated in the early days implored employees to "move fast and break things."

As Facebook explained in its 2012 IPO prospectus:

Moving fast enables us to build more things and learn faster. However, as most companies grow, they slow down too much because they're more afraid of making mistakes than they are of losing opportunities by moving too slowly. We have a saying: "Move fast and break things." The idea is that if you never break anything, you're probably not moving fast enough.

Zuckerberg has since amended the doctrine to "move fast with stable infrastructure," an acknowledgment that as Facebook has gotten bigger and plays a more important role in so many people's lives, it cannot be as care free as it once was.

Still, moving fast remains at the center of Facebook's philosophy.

Compare that to this line in a recent Twitter job listing for a software engineer focused on "deep learning," a type of artificial intelligence.

"Balance out your desire to ship code with your responsibility to get it right."

The message seems to be that perfection, not speed, is the top priority and an employee's most valuable trait. It almost seems to imply that speed is an inherent character weakness among programmers, a bug that must be fixed, or at least tempered, by the organization.

To be fair, Twitter's line about "getting it right" is not included in all of its job listings. It applies only to the undefined intelligence job - and perhaps for good reason, given the power of AI and the impact it is expected to have on society.

But it's an interesting window into Twitter's attitude, given that one of the biggest knocks against the company has been the glacial pace at which it has rolled out new features and products.