What is the difference between Normalize.css and Reset CSS?

The difference is that Normalize css does not unstyle everything it preserves the defaults.and in reset.css there are no visual distinguishable from normal text.

Reset.css will remove all the default styling applied by the browser to give you a blank canvas where as normalize is a base stylesheet meaning its the starting point for your website styles and it styles the default elements to be consistent across the browsers.

Normalize.css preserves useful defaults rather than "unstyling" everything. For example, elements like sup or sub "just work" after including normalize.css (and are actually made more robust) whereas they are visually indistinguishable from normal text after including reset.css