Site pages: - Site pages - this is a site or web area, the user can customize the site pages, site pages are stored in the content database,
You cannot have user code on the pages of a site. Site pages are pages without a title.
Application Page: -
Application pages are an area with a farm. The user cannot configure user settings. Application pages are stored in the WFE (web interface) in the _layouts folder. You can have your own code on application pages. Application pages are ghost pages.
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