In contrast, take a look at the temporary files created by photoshop.
At least on a computer like mine (several years old), you can easily see the difference in the behavior of the software. For example, in photoshop, if you use the smart sharpen filter, you will see rapid changes in the screen preview. However, when you decide to accept the changes, you have to wait while the software modifies the scratch file you are working on. In contrast, a sharpening change in LR is nearly instant. It doesn't have to rewrite a working rasterized file, although it does need to rewrite the rasterized image on screen.
You have often insisted that there is no difference until one saves a file, but that simply isn't accurate. As many of us have pointed out, these two different approaches have functional consequences.