Yes, the “Previous Page” and “Back” buttons are different. Pretty simple actually — Previous Page is akin to PgUp (and NextPage is akin to PgDn), whereas Back is akin to ‘Back’, in the ‘history’ sense like a browser (and literally in the ‘experimental’ browser).
OK, so I work on Kindle. Apparently it’s not just me. Those who actually touch one have a notably higher opinion than those who don’t. Alas, it’s only available for sale on Amazon.com; find a friend or family member who owns one and beg, borrow or steal it for a few minutes to try it [...]