QUOTE(mrmaxx @ May 20 2009, 12:29 PM)

My question is, do 419 scams constitute a subset of phishing or should I report all phishing to both?

I think there's a lot of wiggle room in these definitions. I'd say report them to anyone you can find, let them tell you otherwise.
My own understanding is that "phishing" is where the crook makes an elaborate pretense to be your bank (etc.) and tries to get you to log in in such a way that he can capture your login info, credit card number, etc. He will typically use direct-to-MX bulk mailing and secret websites for this purpose. He doesn't ask you for money, etc. (he will get that himself later).
419ers, on the other hand, are very low-tech swindlers (using freemail, no websites and no direct-to-MX) who try to trick people into thinking they won the lottery, that they can collect money belonging to a dead politician, etc.
The phisher is done with you after one message to you (if you respond, that is). 419s, on the other hand, require a lot of back-and-forth traffic for the crook to suck you further into the scam. That's why it can be useful to report e-mail addresses known to be used by 419ers for collecting replies.
-- rick