publications - Is there a difference between "forthcoming" and "in press"?

Once a paper of mine has definitively been accepted for publication, I typically list it on my CV and in citations as "forthcoming". Other people seem to use "in press" for the same category, and an author once asked me to change my reference to his paper to use "in press" rather than "forthcoming". Do you feel that there's a literal difference in what's conveyed by these two terms, or some difference of connotation? I suspect it simply has to do with conventions in different disciplines.

(Personally, I'm a little bit uncomfortable with "in press", since it suggests that the publisher is at least close to the process of printing the paper. Apart from the fact that that doesn't make sense for online-only journals, I feel funny referring to a paper that I know will appear in a journal issue dated a year and a half into the future as "in press". Actually being printed is a long way off.)

(On the other hand, I suppose that "forthcoming" might be confusing to someone who doesn't know its standard meaning in academia. In theory, someone might interpret it as implying no more than "This is something that I'm planning to write, when I get around to it, and this is the journal I expect to publish in." Obviously, that's not what most academics take "forthcoming" to mean, but any thoughtful person would understand that "in press" implies that you can count on the paper being published.)

EDIT: Obviously, given some of the answers to my question, the way that I thought that nearly all academics obviously interpret "forthcoming" was not correct (assuming that there's not too much weirdness in the sample I've drawn by asking the question here).

Answer

I don't agree with most of the answers so far in one point: The answer depends on your field / area of research, so there is no universal truth about them.

For example in economics I have never seen "in press" and "forthcoming in [journal]" means that it is accepted. If the issue of the journal is already clear some people change it so that it looks like was already published (with a date in the future). (However, most people don't care after that point.)

The only thing where I have seen "in press" is when talking about a book.

So the main point (at least for me) is to clearly state by whom it is "in press" or where it is "forthcoming", as this adds credibility to your claim that it will be published.

However, from your question it is clear that both are common in your area of research and therefore I would just stick with the most commonly used. If you add the journal / conference where it is going to be published it should be clear that it was accepted.