I understand that 7za.exe supports a smaller number of compression formats, but I was curious what else may be different between the two, other than just that?

Having some additional information on these would help me understand some of the trade-offs between the two and help ensure I pick the best one to suit my particular needs.

For example, I wasn't sure if one is faster than the other? Assuming that 7za.exe has support for the archive formats I need, what are the substantive differences between the two in terms of such things as specifications, features, and documented performance?


7Z.exe versus 7Za.exe


According to the Command Line Version User's Guide:

"7za.exe (a = alone) is a standalone version of 7-Zip. 7za.exe supports only 7z, lzma, cab, zip, gzip, bzip2, Z and tar formats. 7za.exe doesn't use external modules."

In contrast, according to 7z Format:

"7z has open architecture, so it can support any new compression methods. Now the following methods are integrated to 7z: LZMA, LZMA2, PPMD, BCJ, BCJ2, BZip2, and Deflate."

Quick Recap

  • 7Za.exe: Standalone and less archive formats supported
  • 7Z.exe: Open architecture able to support any new compression methods moving forward

Choosing One

You could choose 7Za.exe over 7Z.exe for a more light weight and standalone utility that doesn't need external modules to function as expected.

You could choose 7Z.exe over 7Za.exe if obviously 7Za.exe doesn't support the newer archive formats for your need or you foresee the need to use newer archive formats than 7Za.exe will support moving forward since it's open architecture.

  • 1
    It appears that there is not much more to be said about this. I wish that 7za.exe was included in the 7-zip download.
    – lit
    Jul 27 '16 at 14:46
  • 2
    To summarize, if you need features such as LZMA2, pick 7z.exe + 7z.dll (2 files, 1.27 MB), otherwise pick 7za.exe (1 file, 637 KB). Dec 31 '16 at 12:08

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