What's the difference? I don't really know what a Pantheist is but always thought it was similar to being Agnostic.
Theist describes belief in a theistic type god. A personal god, one that can be communicated with, listens to prays, answers prayers, basically the kind of god islam teaches. Theistic gods are the gods of religion, gods that take a personal interest in us and interfere personally with the world. Allah, Zeus, Odin, Osiris, Krishna etc are examples of theistic gods.
Agnostic is the idea that one cannot know either way if there is a god or not.
Pantheists don't believe in a distinct personal god, but rather that the universe/nature is identical with divinity. Basically the universe is god.
Deist describes an idea of god that is the source of everything but that doesn't interfere with it's creation. Most deists believe that the universe was set in motion via the big bang by an unknowable creator, but there's no reason to think this creator cares about us one way or the other. Many deists think this creator is indifferent.
Atheist describes people who simply lack a believe in a god or gods. I would describe myself as an atheist, but I'm an atheist in the literal sense of the word. I don't think theistic gods exist, though I'm open to other types. I suppose you could call me an atheist and an agnostic deist. While I believe I have good reasons for viewing theistic gods as fiction, I can't really say for sure one way or the other whether or not a deistic god or gods exist. I'm open to the idea, just not convinced. There isn't actually a word for an adeist, only an atheist.
Anti-theists are opposed to religion and gods in general, not just theistic gods but often deistic as well. Basically, they think religion is a bad thing, something harmful to society.