The main difference between Bootstrap and Tailwind is that Bootstrap is a component-based set of classes, which is a more traditional way of using CSS. For instance you have card components, button components, a jumbotron, etc.
Bootstrap does have some “atomic” utility classes, but for the most part, there’s a prescriptive approach to the design that intends for you to use certain components for certain elements.
One drawback of this is that it gives you a bit less flexibility (however, you could always customize it).
Tailwind uses much more simple and generic “atomic” classes that only do one simple thing well, and you make your styles by combining a bunch of these wherever you need them.
I hope that helps!