What is the difference between distillation, distillation under reduced pressure and steam distillation?

Simple Distillation: A large number of a liquid boil under ordinary pressure without decomposition. If they contain non-volatile impurities, they are purified by simple distillation. In this method, the impure liquid is vaporised by heating. The vapours formed are passed through a condenser whereas non-volatile impurities are left behind. Condensation of the vapours gives back the liquid in pure form which is collected in a separate vessel.
Distillation under Reduced pressure:Some liquids decompose on boiling under atmospheric pressure. such liquids cannot be purified by simple distillation. they are generally purified by distillation under a reduced pressure.
In this method, the pressure on the liquid surface is reduced with the help of a suitable pump. The liquid, therefore, boils and distills at a temperature which is much lower than its normal boiling point. Thus, decomposition of the liquid is prevented.

Steam Distillation: This technique is applied to separate substances which are steam volatile and are immiscible with water. In steam distillation, steam from a steam generator is passed through a heated flask containing the liquid to be distilled. The mixture of steam and the volatile organic compound is condensed and
collected. The compound is later separated from water using a separating funnel. In steam distillation, the liquid boils when the sum of vapour pressures due to the
organic liquid (p1) and that due to water (p2) becomes equal to the atmospheric pressure (p), i.e. p =p1+ p2. Since p1 is lower than p, the organic liquid vaporises
at lower temperature than its boiling point.