How to delete files that are unrecognizable in the folder? (No, not hidden)

http://imgur.com/a/IBBpD

(First image) When I right click then properties at the "Local" folder in Users/Name/Appdata, it shows that it almost contains 5gb, (Second image) but when I go inside that "Local" folder, then CTRL + A > right click > properties all the files inside it, including the hidden folders and files, the selection only shows 800mb despite it's huge difference.

What is this? Why does this happen? How to delete or at least find the files that cannot be selected or found in there? Thanks. If there are unclear statements or ambiguity, ask right away.