In a standard ZIP, each file is compressed individually. In a "solid" 7z archive, all files are treated as one massive data block.
Unlike some proprietary formats, 7-Zip is open-source and widely considered safe for distributing large software packages. aimstype.7z
If you have many similar files (like versions of the same document or many ROMs from the same console), 7-Zip can find patterns across all of them, resulting in a significantly better compression ratio. In a standard ZIP, each file is compressed individually
If you are looking for the "solid story" behind the file extension and why it’s often preferred over standard ZIP files, it boils down to two main advantages: efficiency and solid compression . The "Solid" Story: Why 7z is Different In a standard ZIP