What is the difference between an alkene and an alkane?

Both alkenes and alkanes are chains of carbon and hydrogen molecules. The chains can be different lengths and each length chain has a different name. 

An alkene is a chain which has a double bond between two of the carbon molecules, making it unsaturated. This means that there is the space for another bond to be formed.

An alkane is a chain which is saturated as all possible bonds are formed.