@James **************
A TM30 is a paper form that you file at immigration. At the bottom of it is a “receipt” part where the officer fills out and stamps. This part is usually affixed to the back of your passport.
The name has stuck with the advent of the online variants like web or app. These don’t do receipts so generally a screenshot suffices. I was told recently the Jomtien office requires the paper receipt. I’ve never used that office so I’m not sure if that’s the case as of today.