Saturated Hydrocarbons :- Those hydrocarbons which have single bonds between the carbon atoms are known as Saturated hydrocarbons. Saturated Hydrocarbons are also known as Alkanes.
Unsaturated Hydrocarbons :- Those hydrocarbons which have double or triple bonds between the carbon atoms are known as Unsaturated Hydrocarbons. Unsaturated Hydrocarbons are also known as Alkenes or Alkynes.
Saturated hydrocarbons have only sigma bonds , which are very stable and difficult to break. However , unsaturated hydrocarbons have pi bonds and they are weaker. Therefore , they are easy to break and will react fast. The electron cloud of pi bond is placed above and below the plane of bonding atom. Hence , electrons will be easily available in unsaturated compounds making it more reactive than saturated compounds.