The atoms of a paramagnetic substance contain even number of electrons. The atoms or molecules of a paramagnetic substance do not possess any net magnetic moment. The atoms of a paramagnetic material contain odd number of electrons.
Every atom or molecule of a paramagnetic substance has its own magnet moment, i. e., its each atom or molecule is a tiny magnet.
In a ferromagnetic substance, there are several tiny regions called domains. Each domain contain approximately 1010 atoms.