This research study has been done in Aljabalein Power Plant at White Nile State. The objective of the study is to compare and differentiate between two types of fuel, light fuel oil (LFO) and crude oil (CRO) used in power plant situated in Aljabalein site. The comparison have been done on different viewpoints including the impact of exhaust gases on the surrounding environment, the performance of engines at different loads, and the operation and maintenance costs. It is found that CRO fuel oil is preferred to LFO fuel due to less operation costs. But it has many disadvantages such as high pollution rates and high consumption of spare parts.