What is distillation and frictional distillation

Fractional distillation is the method  used for the separation of a mixture containing two miscible liquids differing in boiling points by means of distillation using a fractionating column.
In case the difference in the boiling points of the liquids is less than 25K temperature, we use the fractional distillation method.
The apparatus is almost the same as used in distillation. The only difference is that a fractioning column is fitted in between the distillation flask and the condenser. A simple fractioning column is made up of a tube packed with glass beads. The beads provide the surface for the vapours to cool and condense again and again. The fractioning columns obstruct the smooth upward flow of vapours.

Example: A mixture of n-hexane and n-heptane can be separated through the process of fractional distillation.
Put the mixture into a distillation flask. Heat the mixture. The vapours of, n-hexane has a lower boiling point pass through and get condensed in the condenser. n-heptane, which has a higher boiling point, condenses and flows back into the distillation flask.