These two files are present in the templates folder of subscription plan doctype of accounts module.
Please explain the difference between these two doctypes.
Couldn’t locate the two files under the subscription plan folder.
However, the row file would be used when rendering a list of plans and the main HTML file for the individual plan themselves. You can see this working on the blog post page.
The row.html file is how all blog posts are listed. eg: https://frappe.io/blog
The blog_post.html file defines how the main blog post would look like. eg: frappe/frappe/website/doctype/blog_post/templates at develop · frappe/frappe · GitHub