Hi Angelo,
Thanks for getting in touch with us.
The secret is in the name 🙂
sitemap_index.xml is the index of your sitemap. That means, it is like a common file linking out to your actual sitemaps. This is the only one you need to submit to Google instead of individually having to submit a new sitemap every time you install a new custom post type or a new plugin that adds its own products/posts.
page-sitemap.xml is a sitemap file containing links to all your pages.
post-sitemap.xml is a sitemap file containing links to all your posts.
Hope that helps and please do not hesitate to let us know if you need our assistance with anything else.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.
