Ferromagnetic substances are strongly attracted while paramagnetic substances are weakly attracted by a magnetic field. Fe, Co, Ni, Gd, CrO2 are some examples of ferromagnetic substances. They can be permanently magnetized.
Paramagnetic substances are magnetized in a magnetic field in the same direction. In the absence of magnetic field, these substances lose their magnetism. O2, Cu2+, Fe3+, Cr3+ are some examples of paramagnetic substances.