This has to do with the nature of the electron wave function leading to the interactions. In case of diamagnets, it is a closed shell configuration. In case of paramagnets, the spins (generally 1 or 2 outermost s electrons) are non-interacting. The overlapping wavefunctions of the unfilled orbitals when in the solid (band magnetism model) gives rise to strong exchange interaction. An intermediate level text on Quantum theory of solids would provide better understanding. Stated above is a simple language explanation.

To stay with a simplification, you can imagine every material as a sum of small dipole-like particles: 

• Para-magnetic behaviour means that the dipoles are too far from each other to interact, but they align in an external field. Once you remove the latter they come back to a random distribution.
• Ferro-magnetic behaviour means that once aligned by an external field, the dipoles are close enough to each other to interact and keep a preferential alignment when the field is removed. Once you reach the Curie temperature, the thermic agitation is strong enough to break the alignment and the material follow a para-magnetic behaviour

when we apply magnetic field to ferromagnetic materials, the magnetic dipoles are easily aligned along the field direction.  generally, ferromagnetic materials shows large magnetic hysteresis behaviour by doing field variation of magnetic filed at constant temperature.  

depends upon the magnetic hystresis width from M-H measurements.  we choose this material is suitable for  the development of permanent magnetism. naturally, ferromagnetic materials exhibits large  magnetic hystresis width than the paramagnetic materials. 

moreover, diamagnetic materials not response with magnetic field. 

Paramagnets and ferromagnets contain the same magnetic ions. The difference between them arise from two factors: 1) paramagnetic ions are "diluted" in the non-magnetic environment and thus too far away from each other to exhibit collective behavior, and 2) magnetocrystalline anisotropy, being the reason for "easy" and "hard" directions.  Surely, the exchange interactions (the quantum-mechanical reason for (anti)ferromagnetism) need not to be isotropic as well.  Anyway, if there is an energy barrier between two neighboring easy directions, much higher than thermal energy, then we have a ferromagnet.  But even paramagnets, at low enough temperature, become magnetically anisotropic.

          Generally ferromagnets have spontaneous magnetization. but other magnets (dia and paramagnets) does not have the property.