mda vs mdb

[JonWayn]

Other than the file extensions, are there any functional differences between
Access databases and Access Add-ins?

 

[Stuart McCall]

Other than the file extensions, are there any functional differences
between
Access databases and Access Add-ins?

No. The file extension mda allows Access' add-in manager to distinguish
add-in files from 'ordinary' mdb files. The file is structured in exactly
the same way regardless of the extension. Add-in files must contain a table
called uSysRegInfo, which contains instructions as to where to place the
add-in's user interface, eg Tools menu or New form wizard etc. That's the
primary difference, which is all down to what values the developer places in
the table.

Some developers prefer to name library databases with the mda extension,
normally just to make the distinction visible.