The present paper presents a CFD study to determine the heat transfer and fluid flow characteristics of finless and internally continuous finned tubes at different flow conditions. The numerical investigation is executed by solving the conservation equations of mass, momentum, and energy along with two equation-based realizable K-ε model with enhanced wall treatment for thermal and hydrodynamic effects to determine the Nusselt number and the friction factor for finned and finless tubes. The proposed CFD model has been validated with the results available in the literature of previous experimental works. The numerical results showed a good agreement with these experimental ones. It has been found from the present study that increasing fin height and row number leads to a significant enhancement in thermal performance but results in high pumping power for fluid through finned tubes. Also, fin height has more effect on the thermal performance of the finned tube compared to the number of rows. Fin thickness has insignificant effect on thermal performance. Also, a finned tube enhances heat transfer and pressure drop compared to a finless one. In some cases, the heat transfer coefficient is enhanced 9 times in value compared to the finless one. But also, the friction coefficient rises to 2 times in value in the same case. Generally, a finned tube can be integrated with a heat exchanger to become more reliable and efficient.