what does highlighted sections mean? one hard drive has the reallocated sector count highlighted while the other doesnt.
Ok as I understand it the reallocated sector count is where the HD found a bad sector and replaced it with a reserve. It does this to make sure the OS still works even with a bad sector. Now the bad news is it does mean a hardware failure on some level. Some drives can last for years like this but it sounds like you found the one thats causing noises. If the error rate goes up then for sure the drive is failing.
Seagate had some known bad drives a while ago so while I wont recommend against them ( I have one 5 years old still as a backup) I do usually buy WD now.
Back up everything on that drive.
Replace with something like WD640 Black or 1tb Black for speed or Green series for storage.