This post is intended to clarify some of the issues. Nuclear propulsion technology is subject to a high level of classification, so some information must be omitted. Thus the temperature of the near surface sea water can be a limitation on the maximum sustained performance of either type of plant. Both nuclear and conventional plants use steam turbine powered turbine generators for ship's service electrical power. Neither nuclear nor conventional plants develop more power based on the nature of the energy source.
Conventional plants are more thermally efficient and tend to last longer than nuclear plants.
Nuclear plants operate at lower temperatures and pressures and obviously require fewer refuelings. The limitations on power produced for both types of plants lie in the design and construction of the gears, shafting, thrust bearings, and supporting structure, rather than in the turbines or steam generators. High speed endurance is similar for both plants, until the conventional must slow for a few hours for refueling. The limitations on ship's speed are a product of hull design, propeller efficiency, horsepower, vibration, and thermal build up in the propulsion plant. Nuclear plants do not have a de facto advantage in any of these areas, although the smaller hull made possible by the reduction in liquid load is a factor in some designs.