Many of my recent articles are published both as ‘posts’ and ‘pages.’  The difference is that pages’ titles appear in the black bar on the home page as links to the article, whereas posts appear on the home page itself.  Eventually I delete posts.  Accordingly, if you want your comment to be somewhat permanent, comment on the page.  If you are okay with its eventual deletion, comment on the post appearing on the home page.  Clear as mud?  Great!