In using roxygen2, what is the difference, if any, between the effect of tagging a function with 'keywords internal' and that of tagging it with 'noRd'?

Keyword internal means there will be a manual page for the function but it won't be in the documentation index. https://roxygen2.r-lib.org/articles/rd.html#indexing " @keywords internal is useful because it removes the function from the documentation index; it’s useful for functions aimed primarily …