There is a legitimate philosophical difference here, and it involves the difference between voluntarism and service. Voluntarism is the act of doing valuable things that fall just outside the normal scope of governance. Service is more intense: it is a full-time commitment to do the most difficult public works — policing, teaching, social casework.
This was driven home to me last night at the Mud Lounge when a co-worked said he was proud of me and the difference I was making, to which I responded that I didn't feel I was making much of a difference, that I could have had a much greater impact doing something else. I do wonder if I could have gotten into TFA, since they only accept about 1 out of every 8 applicants. (Coincidentally, there was an IBM ThinkPad advertisement in Newsweek that was highlighting Wendy Kopp and TFA.)
Interestingly enough, the TFA website doesn't mention that they have no government funding for next year. I wonder if I can still apply and hope they find funding elsewhere?