Using a painting analogy:
Theists belive in a painter and a painting. The painter painted the painting
Pantheists believe that the painter IS the painting
and Atheists believe that the painting did not have a painter and that it was always there.
To me, this analogy doesn't accurately represent any of the three: theists, pantheists and atheists. Here is how I would portray the different views on deity (I've changed painting to film/movie, and of course this is just my view at the present):
A deist believes in a spirit* filmmaker and a movie. The filmmaker made the movie, pressed play, and sat down to watch.
A theist believes in a spirit filmmaker and a movie. The filmmaker made the movie and is still making edits and additions even while it plays.
A pantheist believes in a filmmaker that is a consciousness of energy* that made itself into a motion-picture.
A panentheist believes in a filmmaker that is a consciousness of energy that made part of itself into a motion-picture leaving a piece of itself behind to observe as the film unfolds.
An agnostic knows there is a movie playing and believes that's all he is able to know.
An atheist knows there is a movie playing and observes that there are natural laws inherent in the film itself that control its development and may even take into account its origin.
(*Note: to some, the spirit and the consciousness of energy may be synonymous depending on one's personal definition of each; both are kind of hazy concepts that are usually defined on a personal level.)