Misconceptions
The winsxs directory is thought to be much larger than it actually is. The directory contains mostly "hard links" to files that exist elsewhere. DIR and Explorer are not aware of the difference between an actual file and a hard link to a file, and so may count the same file several times, adding incorrectly to the perceived disk usage. The disk usage reported by these two programs is as if each hard link *is* an actual file.
Read more about this topic: Side-by-side Assembly