.7z
7z archive
The archive format of 7-Zip, released by Igor Pavlov in 1999. Its LZMA and LZMA2 compression usually beats ZIP, and it supports AES-256 encryption.
Shrinking large files and folders as much as possible.
Opens in 7-Zip, The Unarchiver, Keka, WinRAR, PeaZip
About 7Z files.tar
tar archiveTape Archive
A Unix format from 1979, first made for tape backups. It joins files into one stream and keeps permissions and folder structure, but does not compress on its own.
Packaging folders on Linux and macOS, usually before compressing them.
Opens in the tar command, Archive Utility on Mac, 7-Zip, The Unarchiver
About TAR files