The first thing you do upon starting at Facebook is go to a boot-camp where you learn about Facebook internal systems, architecture, and code so you can contribute early. This is not to say that Facebook does not have, say, data scientists, but everything revolves much more around product. LinkedIn has great product focus too, but the overall mix of roles and skills is more diverse. In any case, payments are not about innovating but leveraging market position to extract shares of revenues.
LinkedIn is rather unique among leading tech companies in terms of the diversity of its business model. LinkedIn has been great in establishing leading position as an elite source of top talent. That is a great position to be in as their customers are not driven by measuring ROI but instead perceive they must participate, or they would be losing out to their competition in recruiting the best talent. On top of all that, LinkedIn revenue has been growing faster and their management of investor expectations has been just about perfect.
Facebook has been less successful, at least initially, in managing investors’ expectations, by mismanaging their IPO and initial growth expectations. LinkedIn timing for IPO was better and their current, as well as eventual prospects for growth are better. Their current market capitalization is $28B, while Facebook is at $218B. For Facebook, that would mean almost $1 trillion valuation, something never seen in history while LinkedIn would be around $110B.
Another set of differences comes from the nature of their data. Facebook's social graph is at the heart of their business, but not at the core of their business model nor even product. LinkedIn has been innovative in launching a quality news feed themselves but that is not at the core of their offerings.
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