They technically have the same policy, but they don't seem to be proactive like Google is.

Also, Facebook doesn't use your name to find your friends, they use your friends list to suggest their friends might be yours as well.

Reason and method are both different.

In the beginning Facebook was far more restrictive in requiring a university email as well as a real name to sign up. If it had instead launched based on an open invitation system and not policed pseudonymous accounts then marketers and trolls would have ensured it remained an insignificant niche site.

If anything, real names were far more critical to Facebook's success than they might be to Google+

I have friends with the facebook names Hiphopopotomus, Joseph Stalin, and Professor X--and they've had these stupid names, that aren't their real names for a long long time--if there is a policy like this in place on FB they aren't really enforcing it.