Is there any difference between alkene and alkylene?

 An alkene is a hydrocarbon consisting of a carbon-carbon double bond. For example – C₂H₄. On the other hand, an alkylene a bivalent saturated aliphatic radical (as ethylene)which is derived from an alkene by opening of the double bond.

For example.. 

Ethene: CH₂=CH₂ 

Ethylene:  -CH₂=CH₂-

Alkylene can also be produced  from an alkane by removal of two hydrogen atoms from different carbon atoms.

Foe example..

Methane:   CH4

Methylene:   -CH₂-