I'm with Sashco, the company who posted that picture. Yes, the prepped sections were taped off in order to clearly mark where the different prep methods were done. After all prep was done, a very narrow groove was cut into the wood before the new stain section to help delineate it a bit more. All of the logs start on the far left with sun-damaged wood with existing stain on it. In addition, all logs on the far right show two heavy coats of the same exact stain in the same color applied by brush. All work was done on a single log wall. The prep is what happens in between and what makes all the difference on the final appearance.
From top to bottom, the prep methods are:
1) Media blasting with crushed glass media alone (no finish sanding).
2) Media blasted with crushed glass media, followed by finish sanding with Buffy Pads (Sashco version of 3M non-woven pads). You can make out a faint line in between the media blasting and the Buffy pad sanding.
3) Power washing, followed by finishing sanding with Osborn brushes. You can make out a faint line between the power washing and the finish sanding.
4) Power washing alone (no finish sanding).
Our goal was to show log home owners how different prep methods affect the final outcome of their stain. They will often choose to sample the stain on some scrap piece of wood from around the house. When the real home staining starts, after all prep is done and they're now applying stain with a sprayer, they find that the color is much darker than their sample. It's why we wrote that blog post and preach "PROPERLY sample" everywhere.
That said, for sure - you can use these different types of wood prep to get the "ombre" stain look that is popular these days. Just don't do it on a full home unless you're really daring and on the cutting edge of log home style. :-)