For a long time I mixed up these types of publishing.
POD (print on demand) is actually a technology that self-publishers use, but you can also find small publishers using it.
Now that I've started to understand the differences, I thought I'd post about it. Basically, self-publishing costs you money. The author pays for their story to get published. If you go with a small, legitimate press, it shouldn't cost you a dime. If the press is small and wants to charge you in order to publish your story, then it's not a small press. It's a vanity press masquerading as a small press.
It's all about the money. If you've thought about self-publishing or going with a smaller press, make sure you study your contract and know what you're getting into.
An example of a legitimate self-publisher with a good reputation is Winepress.
A small publisher who seems legit is OakTara. I stumbled across them after visiting Cindy's blog (she made her first sale to them: woohoo!) and was very impressed with how this publisher emphasizes that while they use POD technology, they do NOT charge the author for anything.
Have you thought about self-publishing or going with a small press? Any experiences with them?
****I may still be confusing vanity and self-publishing: See Michael's comment. Either way, they both cost money, but the money may go to different places for different things depending on whether it's vanity or self-pubbing.