32-bit vs 64-bit

A Microsoft Access installation on Windows is either 32-bit or 64-bit version. On 64-bit Windows either 32-bit or 64-bit version of Access may be installed. MS Access ODBC driver 32-bit or 64-bit version may be installed matching the MS Access installation bitness (but not both).

If MS Access installation is 32-bit, then use ODBC Administrator 32-bit version to set up MS Access ODBC data sources and you have to use the 32-bit version of CompareData.

If MS Access installation is 64-bit, then use ODBC Administrator 64-bit version to set up MS Access ODBC data sources and you have to use the 64-bit version of CompareData.

You can set up MS Access ODBC data sources by running either the 32-bit or 64-bit version of the ODBC Administrator app, that matches the bitness of the MS Access installation, from Windows Start screen or from CompareData Tools menu.

Both 32-bit and 64-bit versions of CompareData may be installed side-by-side, but only 32-bit or 64-bit Access ODBC data sources are available or can be set up (matching the MS Access installation bitness).