The main difference is that the core components from Flowbite are open source under the MIT license, whereas Tailwind UI is a paid product. Another difference is that Flowbite relies on smaller and standalone components, whereas Tailwind UI offers sections of pages.
However, we actually recommend using both Flowbite, Flowbite Pro, and even Tailwind UI as there is no technical reason stopping you from using the best of two worlds.
Learn more about these technologies: