From wikipedia:
"Pseudoscience is a methodology, belief, or practice that is claimed to be scientific, or that is made to appear to be scientific, but which does not adhere to an appropriate scientific methodology, lacks supporting evidence or plausibility, or otherwise lacks scientific status. The term is inherently pejorative, because it is used to assert that something is being inaccurately or deceptively portrayed as science, Accordingly, those labeled as practicing or advocating pseudoscience normally dispute the characterization.
Pseudoscience has been characterised by the use of vague, exaggerated or untestable claims, over-reliance on confirmation rather than refutation, lack of openness to testing by other experts, and a lack of progress in theory development. There is disagreement among philosophers of science and commentators in the scientific community as to whether there is a reliable way of distinguishing pseudoscience from non-mainstream science. Paul DeHart Hurd, who is among the science educators who have taught courses on the topic, wrote that part of gaining scientific literacy is being able to tell science apart from "pseudo-science, such as astrology, quackery, the occult, and superstition"."
The heart of real science is that it consist of methodology's that provide testable predictions. Nothing in the world is real nor is it properly understood at all. This is why theories are constantly changeing and being tested. Scientific theories therefore must be robust ideas that we use to chart the unknown. Scientific theories like say gravity arent true but give us a good handle to grasp the world with. Again by testing a theory like gravity from every direction we are pokeing and proding it from every direction in order to make sure it fits what is observed as closely as possible.
Psuedoscience is the direct opposite. Creationism, astorology, ect are mans attempts to limit and control the scary unkowns instead of making them known. Creationism is incapable of making predictions that can be tested and so is a psuedoscience. Astrology is testable and consistantly fails miserably and so is a psuedoscience.
Hope that helps a little.