Igor Pavlov - 2014-01-11

Yes, there is difference between zip and 7z, when you compress empty files.

7-Zip doesn't request data of empty files for 7z archives, but it request data for zip archives. For example, if empty file is changed after scan stage, the new data will be included to zip, but it will be not included to 7z.

Empty file is not problem for zip archive, since 7-Zip can go back for zip archive and remove all extra things.
But it doesn't go back for 7z archives. So empty file can create empty solid block, that is not too good. So 7-zip doesn't try to read empty file for 7z. And console program doesn't show
Compressing file.ext
line.