The BitcoinCore webpage provides clear instructions on the upgrade process.
“If you are running an older version, quit it. Please wait until it is completely finished. Copy bitcoind / bitcoin-qt (for Linux).”
You only need two files to copy to the folder where Bitcoin is installed.
However, if you look at the entire downloaded installation compressed file, when you unzip it, four folders appear: bin, include, lib, and share. All four folders contain files of different sizes than those previously in those folders in the already running version of Bitcoin. In total, there are 12 files for Bitcoin-Core 26 .vs. Bitcoin Core 25.
Question: Both versions contain 12 different files, so why did you provide instructions to copy 2 files? What if we update all 12 latest files?