After launching a game using either of the 2 activities, the available UIs and functionalities are basically the same.
You can do profiling with Frame Debugger activity.
Even the menu item is called Frame Debugger with Frame Profiler activity.
Even the documentation has the 2 together: https://docs.nvidia.com/nsight-graphics/UserGuide/index.html#frame_debugging_profiling_ui
Thanks for using Nsight Graphics and your question. The Frame debugger allows you to be able to pause and capture a frame for inspection of the rendering and compute calls. With the Frame debugger you can actually step through the API calls. The frame profiler or range profiler allows you the ability to view low-level GPU performance metrics. With the frame profiler you can see detailed GPU hardware statistics across all of the units in the GPU.