>>110011419
sfc /scannow
Invokes the system file checker, which verifies that your Windows files aren't scrambled in some way. Among other things, it checks that they're not corrupted by verifying checksums against The Great Catalogue in WinSxS repository, that they're properly hardlinked to WinSxS, that their ACLs are correct, etc.
dism /online /cleanup-image /restorehealth
This verifies that the WinSxS repository itself is in good health, and redownloads (if you haven't kneecapped it with a memescript) missing/damaged assemblies, manifests etc. if it isn't.
They're actually an excellent pair of tools: I managed to rebuild an entire Windows install from a "deleted system32" situation by alternating back and forth between sfc and dism until it redownloaded and rehardlinked all the files back into place.
Indeed, you should alternate between the commands until both report that there are no errors. This is the part many people skip - as demonstrated, both tools repair Windows installs, but have entirely different responsibilities as part of that process.