They really don’t do the same thing, they complement each other, but each has a function. Pulling from an older thread:
Example - Automatic rewrites is helpful at fixing mixed content errors on your site, always use https does not do that. Whereas always use https comes into play if a visitor types http to visit your site and the site loads without ssl in place…and the visitor leaves and shops at a secure location…with always use https the page always loads as https even if the user does not request that.