Regardless of the various URLs used to access and view thank-you pages we generate, the page itself is generated in only two slightly different versions:
One is a consolidated thank-you page listing all items in the buyer's order (and their respective download links, if any). This is the default page buyers normally view after completing checkout, which can also be accessed via the [%thankyou_link%] template tag you can include in any thank-you email (e.g., this tag is included in the default Common Thank-you Email template we provide for all new accounts). Each Transaction ID in your E-junkie Transaction Log is linked to the consolidated thank-you page we generate for that order. If you redirect buyers to a Common Thank-you Page URL, this page isn't generated and instead auto-redirects to that URL, regardless of whether the buyer arrives there after checkout or via a link provided in their thank-you email.
The other is a product-specific thank-you page only listing a specific purchased item (and its download link, if any), and not any other items purchased in the same order. This is the page buyers would reach if they click the link we provide in the default product-specific thank-you email we send for a download item, which can also be inserted in a product's custom thank-you email template using the [%download_link%] template tag. Each Item Name for a download product in your Transaction Log is linked to the product-specific thank-you page we generate for that item in that order. This page never redirects to a Common Thank-you Page URL, which is what allows the buyer to claim their download purchase even if you specify such a URL.
Both versions include any Common Thank-you Page HTML that you specify in Seller Admin > Edit Preferences; this gets inserted at the end of the page before the </body> tag. Any Product Thank-you Page HTML that you specify in individual product settings gets inserted higher up in the page, after the name of that product. This means of course that a product-specific thank-you page would only have that item's Product Thank-you Page HTML plus any Common Thank-you Page HTML, omitting any Product Thank-you Page HTML you'd specified for other items purchased in the same order. The consolidated thank-you page would have Product Thank-you Page HTML for every item purchased in the order, followed by your Common Thank-you Page HTML at the bottom.