Comparing 7z.exe and 7za.exe

Solution 1:

7Z.exe versus 7Za.exe

Comparison

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.