It's no secret that I have a day job. Most of us have to hold down a job to pay the bills. We may curse the job while we are doing it, but we're glad for the pay when the bills come due. I'm fortunate to also have work. My work is not my job. I do my job to earn a living; I do my work because I am living. Not everyone who wants a job has one, but no one with work can avoid it--not and stay sane. Your job may stress you out and wear you out, but your work will get you out of bed in the morning and keep you up late.
The small minded among us will sneer and call someone else's work a "hobby" simply because the work doesn't pay (and you may have to even pay for the privilege of doing it). I've known plenty of folks who have wasted money on hobbies to buy fishing boats and golf clubs that are soon surplus in life, but it's hard to overspend on your work.
I'm lucky that all my work requires is a working computer or pen and paper. Lord knows I don't blog, or write stories, or hack out bad poetry because it's my paying job. It's not my job, but it is my work.
As with so many important concepts, the distinction between my job and my work was one of those indefinite feelings that I couldn't really articulate until I heard Seth Godin explained it.