What is the difference between hydrogenation and hydrogenolysis?

Hint: We have to remember that for the hydrogenation reaction which requires a catalyst it occurs at the normal condition of temperature and pressure. And hydrogenolysis is a catalytic chemical reaction.

Complete answer:
We must have to know that the hydrogenation reaction occurs between the substance and the molecular hydrogen by the addition of pairs of hydrogen atoms to the unsaturated compounds which requires a catalyst and it occurs at the normal condition of temperature and pressure. But in the case of hydrogenolysis reaction, it occurs by the cleavage of carbon-carbon or carbon-heteroatoms single bond by the addition of hydrogen. The hetero atoms may be oxygen, nitrogen or sulphur. And hydrogenolysis is a catalytic chemical reaction.
The non-catalytic hydrogenation reaction also occurs at the presence of very high temperature and it reduces double bond or triple bond into hydrocarbons. The hydrogenation reactions have a total three components and that is, one unsaturated substrate, hydrogen and a catalyst. And this reduction reaction mainly occurs at different conditions like high temperature and pressure. It also depends on the substrate and activity of the catalyst.
The hydrogenolysis reaction is almost similar to the hydrogenation reaction. It also requires the catalyst. And it may accomplish the atmospheric pressure. And this hydrogenolysis is used for the vegetable oil refining process of largest production capacity. And it is used in the petroleum refineries it is conducted on a large scale to remove sulfur from feedstock, releasing gaseous hydrogen sulphide gas.

Note:
We also remember that the hydrogenation reaction occurs between the substance and the molecular hydrogen by the addition of pairs of hydrogen atoms to the unsaturated compounds which requires a catalyst and it occurs at the normal condition of temperature and pressure. But in the case of hydrogenolysis reaction, it occurs by the cleavage of carbon-carbon or carbon-heteroatoms single bond by the addition of hydrogen.