To me... anything that becomes a permanent modification is a build. Solar panel permanently mounted on the hood, tire carrier, cutting stuff for clearance, stuff that can't be undone without buying replacement parts. I also feel that it's a build when someone puts in the time to research, experiment, and put something together that's useful to them as a build. For instance, I'm by no means the first to do it, but I was one of the few to execute and give info out to those that want to convert to 17s. I've also done some things that people question, like adding ceiling storage space, but low and behold someone took my idea and started manufacturing it way better than mine and was somehow THE best thing ever... just saying. My build was meant to help people, not showing off. I've definitely added way more things as my gear and priorities change.
If I'm pulling out the center seat of the second row to put the fridge in, that's not a build evn though I've permanently ran a power socket from my secondary battery to it. However, the secondary battery with power ran to the rear fuse box with intelligent Redarc dc/dc charging, GoPower dual bank solar controller, and Lensun 110W hood mounted solar panel is considered a build.
Again, this is my personal opinion about this topic so take it with a grain of salt.