I did several philosophy of science courses on my degree and although everybody knows about Sir Karl Popper and Thomas Kuhn less people know about Lakatos; He had a lot to say about pseudoscience - things that look a bit like science (to gain respectability for their ideas?) but fundamentally differ from real scientific theories.
According to the demarcation criterion of pseudoscience originally proposed by Lakatos, a theory is pseudoscientific if it fails to make any novel predictions of previously unknown phenomena, in contrast with scientific theories, which predict novel fact(s). Progressive scientific theories are those which have their novel facts confirmed and degenerate scientific theories are those whose predictions of novel facts are refuted. Lakatos's own key examples of pseudoscience were Ptolemaic astronomy, Immanuel Velikovsky's planetary cosmogony, Freudian psychoanalysis, 20th century Soviet Marxism, Lysenko's biology, Niels Bohr's Quantum Mechanics post-1924, astrology, psychiatry, sociology, neoclassical economics, and Darwin's theory.
There is a very good article on the LSE's website including a recording from the early seventies where he explains the difference between science and pseudoscience.