I've released a 64-bit version of Mp3tag a few days ago and received a few questions about differences between the 32-bit version and the 64-bit version.
To make it short, there should not be any noticeable differences except for two things:
The 64-bit version uses 64-bits to address memory and is no longer limited to 2 GB per application. While the Library feature of Mp3tag is already a very viable solution for large libraries, loosening the memory restriction is one of the key benefits of 64-bit.
The 64-bit version has no support for TAK. TAK is a closed-source codec that is made available in Mp3tag by utilizing a DLL. This DLL is unfortunately only provided as 32-bit version. 64-bit processes cannot load 32-bit DLLs.Edit: Mp3tag v3.17 now also contains a 64-bit version of TAK.
Mp3tag 64-bit can only be installed on 64-bit versions of Windows. The recommended path is to uninstall the 32-bit version before upgrading — the uninstaller has an option to keep your configuration settings. If you install without prior uninstall, no harm is done and the 32-bit version is kept as a leftover on your system. You can remove it manually then.
The standard installation folder of the 64-bit version is at
which differs from the standard installation folder of the 32-bit version at
C:\Program Files (x86)\Mp3tag
You can keep all your configuration settings and can use them also with the 64-bit version of Mp3tag. It's very recommended to backup your configuration settings before installing any software that is in Beta status. From Download and Installation
To backup your configuration settings, please choose File → Save configuration.
To restore the backup, unzip the backup archive to the folder that opens when you choose File → Open configuration folder. Close Mp3tag before copying any files to ensure that all files can be written.