Whenever a game has been shuffled from the Wii U to the Nintendo Switch, most people expect the Switch version to see some graphical improvements. Some titles, like Mario Kart 8 Deluxe see improved resolution, framerate, and even new modes. With Bayonetta 2 (which comes bundled with a code for the original Bayonetta), it appears the graphical differences are rather minor.
Nintendo World Report has put up two videos that show the game running on both consoles. The Switch version appears darker overall, bu that could be due to capture equipment. The Switch games load much quicker, which is a great improvement. Check out the videos for yourself!