Bit of both.
At work, I am very extrovert-ive, since I am a server. I go up to people without holding back, no matter if I even think they are cute and ask them if they want drinks, snacks.... whatever. I am also very extrovert-ive around people I get to know.
However, outside of work, I am completely introvert-ive. My brother's girlfriends? I never really met with any of them face to face, because I avoid them. Same with his friends. My friend's friends, same thing. I just try to stay away. I get very, very shy outside of work.
I guess it's true though, work and personal lives are completely, completely different.