|When you do the disc properties it shows the usage from all files and folders with system root files and system restore files. and allocated cluster size.|
When you do the file/program properties it shows only the actual size of the files and programs. It does not show system root and also system restore files....These are kept hidden to protect the files from accidental corruption.
About the allocated cluster size.. files are stored in data blocks or clusters. The size of these clusters is determined at formatting and what operating system is being used.
Each file is given a full allocation of clusters to write the data to, although the file may not require or use the full cluster size it is dedicated to that file. This is what you see in the disc properties of the drive....all the allocated clusters (used and unused space per cluster) for each file.
what you see in the all programs and files/folders select properties is the actual file/folder size less the dedicated cluster allocations
Think of each cluster as 10 blocks of available storage space. You create a file that uses only 8 blocks. The 8 blocks is the actual size the file is report to be....but when viewing as allocated disc space the file is shown to be 10 blocks in size.
This seems wasteful but actually allows for faster retrieval of the stored data because the search takes less time looking for the file....
Change Is Good